# Canon 7Dii vs Nikon D750 Dynamic Range Test



## MichaelTheMaven (Nov 1, 2014)

I was happy to get my Canon 7Dii yesterday and being in the middle of reviewing the Nikon D750, I decided to put them both through a Dynamic Range test I have been working on. I know it is an Apples to Oranges comparison, but I was curious none-the-less. 

Im not a huge fan of, nor believed a certain testing website for various reasons, and have always read their scores with skepticism because their methodology is mostly proprietary and scoring system whacky. In fact, I have long wanted to come up with a DR test simply to confirm or deny their DR tests to some degree.

I am long time (12 years Canon owner and shooter vs 3.5 years of Nikon), so if anything I would naturally be more biased towards Canon, but in this test I think we are looking at a DR for the 7Dii very similar to that of the Canon 5Diii.

In the past, some of you have been very insightful with suggestions and tips to improve my tests, and therefore I invite your scrutiny and suggestions. Many others of you have ridiculed me, which also actually improved the quality of my tests, so I guess I invite that as well, as long as there is some creativity involved in the ridiculing. 

What do you guys think I can do to improve this beyond the obvious (cropping straight).

*What would be a good way to figure out total DR and noise cut offs?*

http://www.michaelthemaven.com/?postID=3431&canon-7dii-vs-nikon-d750-dynamic-range-test-by-michael-the-maven

In any event enjoy!


----------



## YuengLinger (Nov 1, 2014)

OH, boy. Here we go.


----------



## lintoni (Nov 1, 2014)

YuengLinger said:


> OH, boy. Here we go.


----------



## retina (Nov 1, 2014)

MichaelTheMaven said:


> I was happy to get my Canon 7Dii yesterday



congrats, don't forget to post some photos!



MichaelTheMaven said:


> I know it is an Apples to Oranges comparison



do you, really? 



MichaelTheMaven said:


> What do you guys think I can do to improve this



hmm.. you could start by not wasting your time with a useless test like this.
it's clear that Sony/Nikon sensor has more DR in this current generation of cameras, this has been tested a billion times now.
go out there and shoot, improve your photography skills. life is short.


----------



## 2n10 (Nov 1, 2014)

Thank you for doing the testing and braving wrath. It is apparent that there are 2 schools of thought and that as you have acknowledged while you are most likely biased towards Canon your test is biased to the Sony sensor since you are only looking at the dark end of the scale.


----------



## fragilesi (Nov 1, 2014)

Excuse my ignorance ( please  ).

But why are the Canon pictures so much darker with "real" black while the Nikon is just a washed out grey colour?


----------



## East Wind Photography (Nov 1, 2014)

Well I tend to agree. A DR test is not all about shadow noise. All this test shows is that at ISO 100 the sony sensor has better noise and shadow recovery. Would liked to have seen the conprison of all three cameras at the highlight end using the same settings.

Also would be nice to see this comparison at a few ISO ranges up to 3200 or higher if there is a useful comparison to be had. It is well known that most sensors yield better shadow DR at higher ISOs and less so on the highlights.

I dont recall if you mentioned this but when comparing crop vs full frame you also need to adjust your distance to the subject to compensate for the crop factor. While it may not affect the DR and shadow tests it will affect the percepted noise levels since you need to enlarge the full frame image to match that taken with the the crop sensor. For those that are really anal you can even go as far as ensuring the subject covers the same number of pixels on both sensors so the resolution matches in the tests.

I would not say you are comparing apples and oranges. YOu just need to be more comprehensive in the tests. As you can see there are many ways to run tests and no one test will give you all of the answers.


----------



## mjbehnke (Nov 1, 2014)

Why are you comparing a Canon 7Dii Crop Sensor to a Nikon D750(sony) Full Frame Sensor?


----------



## bgosselin (Nov 1, 2014)

Can you also do your tests with jpeg out of the camera? Different ISO would be nice. My understanding is that Canon sensor DR are essentially the same as Nikon at ISO 800 and higher.


----------



## StudentOfLight (Nov 1, 2014)

Hi Michael,
Regarding the D750... a certain testing website states that the dynamic range (straight out of camera) for the D750 at ISO 100 to be about 13.7 stops. You mentioned that there is potential for highlight recovery. If there is one stop of highlight recovery available then their result correlates directly with what you captured. 

In a 14-bit-world having 13.7Ev in a single capture is quite sensational. I can't wait for 18-20MP full frame camera with 16-bit on-sensor ADC.


----------



## StudentOfLight (Nov 1, 2014)

bgosselin said:


> Can you also do your tests with jpeg out of the camera? Different ISO would be nice. My understanding is that Canon sensor DR are essentially the same as Nikon at ISO 800 and higher.


I think the point of Michael's test was to demonstrate the maximum DR of the cameras, which would be at their respective low-ISO-setting (e.g. ISO 100). If you were shooting with the Nikon D750 in a High Dynamic Ranged scene would you rather shoot at ISO 800 and thereby sacrifice some potential highlight and/or shadow details or would you rather shoot at ISO 100 which would give you the maximum range?


----------



## neuroanatomist (Nov 1, 2014)

StudentOfLight said:


> If you were shooting with the Nikon D750 in a High Dynamic Ranged scene would you rather shoot at ISO 800 and thereby sacrifice some potential highlight and/or shadow details or would you rather shoot at ISO 100 which would give you the maximum range?



I would rather select the aperture for the DoF I want, and the shutter speed based on motion in the scene (if any, and if I want to freeze it). If that means sacrificing some potential highlight/shadow details because I need to use higher than base ISO, so be it. 

As for the DR of the 7DII, I'll just wait for DxO to test it and post the measurement data.


----------



## Skulker (Nov 1, 2014)

fragilesi said:


> Excuse my ignorance ( please  ).
> 
> But why are the Canon pictures so much darker with "real" black while the Nikon is just a washed out grey colour?




Because he's deliberately messing up the shots taken with the Canon? No surely not! After all he's already said he favors Canon and I'm sure he wouldn't tell porkies just to get traffic onto his website.


I'm convinced this is a fair and reasonable test. No, you're not convinced? Well as good as he can do then. Still not convinced? How about maybe he knows what he's doing and maybe his main interest is not a fair and reasonable test?


Now the most important question for me. How do I stop the website from telling me this thread exists?


----------



## tayassu (Nov 1, 2014)

I don't understand that whole DR thing... I get what it is about, but with the RAW flies of my old 7D I can bump up the shadows well enough, even @ISO3200! And that should be enough not to have every fifth thread going on about this!


----------



## tcmatthews (Nov 1, 2014)

MichaelTheMaven said:


> I was happy to get my Canon 7Dii yesterday and being in the middle of reviewing the Nikon D750, I decided to put them both through a Dynamic Range test I have been working on. I know it is an Apples to Oranges comparison, but I was curious none-the-less.



As you have stated this is an Apple to Oranges test. Quite frankly if I was buying the 7Dii I would not be buying one for DR. End argument.


----------



## StudentOfLight (Nov 1, 2014)

neuroanatomist said:


> StudentOfLight said:
> 
> 
> > If you were shooting with the Nikon D750 in a High Dynamic Ranged scene would you rather shoot at ISO 800 and thereby sacrifice some potential highlight and/or shadow details or would you rather shoot at ISO 100 which would give you the maximum range?
> ...


So you are saying that your goal would not be to capture the maximum DR of the scene. That is a fair choice on your part and of course there are situations that call for creative choices and I respect that.

I would like to point out that you didn't quote me fully. My first sentence in the (relatively short) paragraph was that I thought Michael's goal was to demonstrate the maximum DR of the camera(s) so my example was related to that assumption. Hence, in my example the goal is maximum DR capture so using a higher ISO would result in failing to achieve that goal.


----------



## klickflip (Nov 1, 2014)

Firsty well done and v brave doing this and posting! Can I ask how the hell have you got so much noise in ISO100 images ? They look like is 128000 shots. A well exposed shot sat 100ISO even a predominantly dark image should not have that much noise in it. - Are these huge crops into the frame and have you lifted the exposure 3 stops or something? 

If you are in the envious positions to have 7DII and D750 would it not be more beneficial to set them up side by side and shoot some real tests of landscape , cityscape , portrait and still life etc.
Id be really interested to see the difference side by side. 
Now we all know that the D750 will be a fair bit cleaner and esp in the shadows depending how much you recover these for artistic reasons. But as long as you don't go mad and maybe recover slightly shadow and highlights to get a nice result which is what most people do. 

Try some interesting examples shooting into the sun at dusk etc and lets see what these awesome babies can do!  
Please seriously stop wasting you time on photographing charts!


----------



## MichaelTheMaven (Nov 1, 2014)

Sorry about not explaining more carefully, good feedback. 

Yes, essentially I am looking for the total DR I can squeeze out of a RAW file but recovering in the shadows, so both files have +2.6 Exposure (the point where the first swatch overexposes) and shadow recovery all the way. Part of the problem is I cannot import the 7Dii into Camera RAW and have to use RAW Therapee which I am totally unfamiliar with. 

I believe it is Apples to Oranges in some regards because it is full frame vs crop (and photo site size seems to effect noise performance), but the reason I wanted to test is because they both have the most current sensors and processors from respective companies.

Im basically trying to get as many 1/3 stops of range captured with one end (the highlights) being clipped out. There is some room for recovery there, so its limiting my ability to find total DR, but all things being equal, it allows me to get something a little more illustrative than just recovering some shadows in an image. 

Thank you for the suggestion to get out and shoot. My Dad just dropped off his Tamron 150-600, Im going to take it down the to beach! Im listening to all your feedback, so thank you for that as well. 

M


----------



## mjbehnke (Nov 1, 2014)

I still think you need to compare crop sensor to crop sensor. Not crop sensor to full frame. Proves nothing, except that full frame sensors have better DR.

Unless I'm missing your point in all this? Fill me in?


----------



## Marsu42 (Nov 1, 2014)

StudentOfLight said:


> In a 14-bit-world having 13.7Ev in a single capture is quite sensational. I can't wait for 18-20MP full frame camera with 16-bit on-sensor ADC.



Only 13.7ev dynamo race and 14 bit resolution? That's pathetic - with my 6d and Magic Lantern, I'm getting 14.5 stops and 16bit raw files.

Without ML, I admit I'd be quite lost with what I shoot - but once you accept the usability hassle, there's really little reason to complain about dr on Canon (except 1d/7d2 which don't have ML (yet for the latter)).


----------



## privatebydesign (Nov 1, 2014)

Specifically on the testing I'd say you have a couple of issues.

The first, from your strips the Canon's are displaying more DR than the Nikon, why do I say that? Because the black is darker, DR is the difference in luminosity between the brightest white and the darkest black, in those simple terms the Canon strips perform better. Now I am not suggesting the Canon has 'more DR', what I am saying is there is a flaw in your methodology. Both black points should display the same value, 0.

Second, for the 7D MkII to actually test better than the 5D MkIII also seems to point to an error in methodology. We all know the downsampling meme, without knowing sensor area sampled and reproduction ratios we don't know if we are comparing like for like or turnips to tulips.

Third, the wedge numbers seem to indicate you are not getting even illumination across your step wedge. Surely all the numbers should have the same values? You are getting falloff across the wedge. The illumination has to be completely even.

Lastly, whilst these tests do have some merit, I find a far more beneficial test is actual post processed results, that is, don't use zero post processing because it isn't 'fair' and isn't how we actually get the best out of our gear. Besides, Nikon have long been suspected of cooking their RAW files. A truer test of actual end results is to process both files to the best abilities you can with the software you would use, and dn't be surprised if other people get different results with different software.


----------



## YuengLinger (Nov 1, 2014)

Why not convert with Canon DPP? It shipped with your 7DII.


----------



## AlanF (Nov 1, 2014)

MichaelTheMaven said:


> I was happy to get my Canon 7Dii yesterday and being in the middle of reviewing the Nikon D750, I decided to put them both through a Dynamic Range test I have been working on. I know it is an Apples to Oranges comparison, but I was curious none-the-less.
> 
> Im not a huge fan of, nor believed a certain testing website for various reasons, and have always read their scores with skepticism because their methodology is mostly proprietary and scoring system whacky. In fact, I have long wanted to come up with a DR test simply to confirm or deny their DR tests to some degree.
> 
> ...



Does calling yourself "The Maven" mean that you consider yourself the expert?


----------



## MichaelTheMaven (Nov 1, 2014)

The 5Diii test is there as well, thats full frame to full frame.

Same strip, same exact settings on both cameras same everything. I have a hard time differentiating between stops 32/33 and higher on the Canons due to their noise. The D750 is much cleaner and easier to differentiate, more visible, distinct shades in deeper tones. Its clear to me. I try to frame up the strip edge to edge in both cameras. when I shoot it so yes the focal lengths are different. 

The strip is calibrated plus the strobe & tripod do not move, not sure how that would explain such different results between the two.

There was some exposure and shadow recovery on both, no noise reduction. Ill have to play with it more once the 7Dii files are supported by Camera RAW. 

Canon DPP will only convert to tiff and JPEG files, unless I am mistaken. 

Thank you for the feedback.

M


----------



## MichaelTheMaven (Nov 2, 2014)

A Maven is an both an expert in a particular field, AND someone who is willing to share his knowledge about that field, I first learned about it from the book "Tipping Point" by Malcolm Gladwell, and it has stuck for me. 

I consider myself a student of all things who is willing to learn as much as possible and then share. Whether someone considers me an expert depends on their personal perspective. I teach beginning photography, so from the students perspective in terms of learning photography, I better be an expert...right? 

M


----------



## East Wind Photography (Nov 2, 2014)

MichaelTheMaven said:


> The 5Diii test is there as well, thats full frame to full frame.
> 
> Same strip, same exact settings on both cameras same everything. I have a hard time differentiating between stops 32/33 and higher on the Canons due to their noise. The D750 is much cleaner and easier to differentiate, more visible, distinct shades in deeper tones. Its clear to me. I try to frame up the strip edge to edge in both cameras. when I shoot it so yes the focal lengths are different.
> 
> ...



As I mentioned before you are not testing the complete DR of the sensors. You also need to show the white highlight area. Showing the shadow part of the DR is not the complete range. I'd like to see how the other end looks at the same exposure and where the highlight detail is lost.

The only thing you care comparing here is shadow detail at ISO 100, not dynamic range.


----------



## jrista (Nov 2, 2014)

Thanks for the test, Michael. I'm glad you ran the test. 


Given that you lifted the shadows, I think that can explain why they look brighter on the D750...there IS a lot more dynamic range to be had there. In my experience, lifting Canon shadows looks exactly like your Canon results, where as lifting A7r shadows look exactly like your D750 results.


I do think that showing the entire wedge, from the highlights to the shadows, both unprocessed as well as processed, and including the settings you used to process them, would help provide a more balanced review. It should head off the most predictable of human responses (which is quite prevalent on these forums) as well. ;P 


Anyway, looking forward to seeing the full step wedge in both OOC and processed versions.


----------



## Mt Spokane Photography (Nov 2, 2014)

Skulker said:


> Now the most important question for me. How do I stop the website from telling me this thread exists?


 
You can go to your profile and choose the ignore boards option. Now, if there were only a board for DR and for trolling posts (2 boards). Then we could ignore them and those interested could use them.


----------



## ajfotofilmagem (Nov 2, 2014)

This is not a test of DR. The way it was done is a test "lift the shadows." : 

A true test of DR will compare similar cameras, photographed with equal illumination at ISO 100, 200, 400, 800, 1600, 3200, 6400. 8) I know many photographers who never use ISO 100, but interestingly, many of the DR testing has only ISO 100, deliberately under-exposed, and corrected in PP.  

Shooting with the correct exposure is so difficult today?  
Is it really necessary to do tests that simulate user error? :-X


----------



## MichaelTheMaven (Nov 2, 2014)

jrista said:


> Thanks for the test, Michael. I'm glad you ran the test.
> 
> 
> Given that you lifted the shadows, I think that can explain why they look brighter on the D750...there IS a lot more dynamic range to be had there. In my experience, lifting Canon shadows looks exactly like your Canon results, where as lifting A7r shadows look exactly like your D750 results.
> ...



I see what you are saying here. Its black and white to me, but without showing what I am actually doing and how I am trying to get these 41 calibrated steps all in one shot, I can see how it would be confusing. Im out shooting now, Ill post something tonight to show how I am clipping off that first step in RAW, and then squeezing everything I can out of the shadows.

I know some people believe this is not useful or not a DR test, but I think the results are pretty obvious. If you have a better solution or idea, I would still love to hear it. 

M


----------



## takesome1 (Nov 2, 2014)

It would be nice to see an overall test of the DR of the 7D II vs whatever. This test isn't that, it is just a shadow test in a narrow set of parameters. 

I bought the 7D II as a wildlife camera for focal length limited situations and for packing.
Testing the 7D II at 100 ISO is useless for the the type of photography that this body is designed toward.

So I will watch for the next test to come along to see if it will show how the camera performs in real world situations.

Or maybe I will just check it out myself once mine arrives.


----------



## jrista (Nov 2, 2014)

MichaelTheMaven said:


> jrista said:
> 
> 
> > Thanks for the test, Michael. I'm glad you ran the test.
> ...




I'm someone who believes that the D750 has significantly better DR than any existing Canon sensor. I'm right there with you. I've been waiting for Canon to fix their sensor read noise problems for years, and I'm pretty fed up with their lack of progress. They may have reduced banding, that's good...but your test indicates that overall...nothing has really changed. Color noise is just as big a problem on the 7D II as it has always been (compared to the 5D III, you don't even need the D750 image to see that.) Personally, for all the time Canon invested in the 7D II, I find that extremely disappointing. It's disheartening, but, that's just my opinion. (I can only hope that sometime next year, Canon demonstrates some radical new sensor technology that improves IQ across the board, reduces read noise to unprecedented levels, etc. (I say unprecedented, because with Canon's turnaround rate for releasing new models, any new sensor technology they release will need to stand the test of at least three years...and all their competitor sensors that come out within that time.)


I just know that the resistance to and downright denial of the notion that improved DR matters, or that anyone is even remotely capable of performing a valid IQ test, or that Canon cameras might have a problem with anything, is extremely high here. I think your test is valid. It should may DTaylor happy, however I'm pretty sure if/when he comes along, he'll have some way of 'debunking' what your test clearly shows.


Your test may need fine tuning to get the best apples-to-apples comparison, and without a doubt more information will help keep the skeptics satisfied. I would show the full length of the test strip, show exactly what settings you are using in RawThearapy for your processing, and even share the RAW files themselves. That's the only thing you can do if you really want anyone to take you seriously. (And even if you provide everything, there are still going to be people who deny that any of it matters...)


I personally take your results seriously, but I've had my own first hand experience with cameras that use Sony Exmor sensors, so I'm not surprised by the results.


----------



## neuroanatomist (Nov 2, 2014)

jrista said:


> I'm someone who believes that the D750 has significantly better DR than any existing Canon sensor.



Me, too. 




jrista said:


> I just know that the resistance to and downright denial of the notion that improved DR matters, or that anyone is even remotely capable of performing a valid IQ test, or that Canon cameras might have a problem with anything, is extremely high here.



No. 

There is general acknowledgment that more DR is desirable. Certainly some people/organizations are capable of performing valid IQ tests, but there are also many poorly done and biased tests out there, and cases where valid measurements are interpreted/summarized in a biased manner. As for Canon cameras having problems, that has certainly occurred and been widely acknowledged. 

What there is high resistance to is the idea that 2-3 stops less DR and more noise when shadows are pushed >2-3 stops mean that Canon sensors deliver (in your words), "...poor, sub-par, unacceptable IQ." There is downright denial of the idea that DR is the only performance metric of a camera system that matters to most people. 




jrista said:


> I personally take your results seriously, but I've had my own first hand experience with cameras that use Sony Exmor sensors, so I'm not surprised by the results.



I doubt anyone would be surprised that a FF Exmor sensor has more DR than an APS-C Canon sensor. However, I would not be at all surprised to see certain individuals claiming that means the 7DII delivers poor IQ and shows a lack of innovation by Canon, and other such foolishness.


----------



## privatebydesign (Nov 2, 2014)

jrista said:


> I just know that the resistance to and downright denial of the notion that improved DR matters, or that anyone is even remotely capable of performing a valid IQ test, or that Canon cameras might have a problem with anything, is extremely high here. I think your test is valid. It should may DTaylor happy, however I'm pretty sure if/when he comes along, he'll have some way of 'debunking' what your test clearly shows.



What an inflamatory thing to say, kinda like shouting fire in a cinema, and I believe in the USA that is illegal. It is also a gross misrepresentation of the opinions that people here actually have, but you know that and did it anyway.........

So anybody that questions methodology, as I legitimately did and included specific areas of concern, is automatically labeled in denial of the holy Exmor scripture? 

Way to go to incite the response you criticise people for and lay the foundation for the kinds of discussion you always claim you are interested in.


----------



## ajfotofilmagem (Nov 2, 2014)

We all know that (until proven otherwise) Exmor sensor that has more DR than Canon sensors *IN LOW ISO*. So, DR tests would be most useful to compare Exmor versus Canon in ISO1600 and above. :

Someone wants to apply? 8)


----------



## StudentOfLight (Nov 2, 2014)

ajfotofilmagem said:


> We all know that (until proven otherwise) Exmor sensor that has more DR than Canon sensors *IN LOW ISO*. So, DR tests would be most useful to compare Exmor versus Canon in ISO1600 and above. :
> 
> Someone wants to apply? 8)


Scientific results should be repeatable. The fact that we have multiple methods to come to similar results would lend credibility to given claim. The process of verifying a claim is not a waste of time. If all people would just accept anything at face value then liars, cheats and deceptive quacks would run amok.

I've looked though my LR catalogue and here are my percentages of shots taken at different ISO settings:
50&100 - 29.3%
200 - 16.1%
400 - 14.6%
800 - 8.1%
1600 - 11.8%
3200 - 5%
6400 - 4.8%
12800 - 1.5%
25600 - 0.2%
51200 - 0.0%
102400 - 0.5%

Until I actually did this exercise I didn't realize how much I shot at low ISO. If I had just stuck with what my feelings were I would believe that I shot a lot more at 800-3200, but in reality that simply is not the case. Numbers don't lie (until they get to the statistician)


----------



## Don Haines (Nov 2, 2014)

ajfotofilmagem said:


> A true test of DR will compare similar cameras



There are lots of valid reasons for testing dis-similar cameras... One might be asking how the 7D2 compares to the 5D3.... one might want to know what the differences are between old tech and new tech.... between FF and Crop, between 4/3 and crop, between Canon, Nikon, and Sony... Lots of questions to be asked here and even more answers sought. We THINK we know the answers, but until testing is done, we are just guessing.


----------



## Marsu42 (Nov 2, 2014)

neuroanatomist said:


> privatebydesign said:
> 
> 
> > jrista said:
> ...



Yay, ladies and gentlemen, the game is ON again after one of the contestants withdraw from the first round from pure exhaustion. How many pages will the second round last? Make your bets and watch the show, now live on CR! :->


----------



## ajfotofilmagem (Nov 2, 2014)

Don Haines said:


> ajfotofilmagem said:
> 
> 
> > A true test of DR will compare similar cameras
> ...


Don, you forgot the most important part of my message: Tests comparing a parameter (for example DR) must minimize all other possible variables. 

I understand that some want to know "how much" of a difference between equipment of different categories and purposes. But the bottom line is always getting stuck in tests at ISO100 purposely under-exposed to lift the shadows in PP. :-[ This seems to me an excuse to prove to yourself something like "my dick is bigger than yours"... :-X


----------



## jrista (Nov 2, 2014)

Marsu42 said:


> neuroanatomist said:
> 
> 
> > privatebydesign said:
> ...




I have no intention of playing any games. I said what I said, in the way that I said it, because I believe that is how a core group of members in this community...operate. They break down and deny every test ever done, and always find some way of labeling them flawed, or incomplete, or unfair, or something like that. I call that denial.


People are free to take offense to that, or ignore it and just keep on making photos, or maybe actually break out of their comfort zone and give another brand a try if they are really curious about the truth (damn what anyone else says, including me, prove it to yourself if you are wondering what's what...hopefully with the realization that _it isn't *just *low ISO DR that is better on competitors anymore_...the A7s brings better DR throughout the entire ISO range). Otherwise, I'm not here to participate in a war.


----------



## Marsu42 (Nov 2, 2014)

jrista said:


> Otherwise, I'm not here to participate in a war.



I believe you, and I have the impression you're not out for flamewars but simply want to argue a point. Personally, I have no doubt that the current Nikon/Sony sensor tech blows the current Canon sensors out of the water concerning dynamic range, so I'm a bit lost what there is to argue about at all.

It's simply about you want more than 11.5 stops for whatever reason or not - all reasons are valid, everyone is free to use his/her equipment as he/she pleases, even if it's simply for convenience and more error margin when exposing.

As for arguing testing conditions, I have plenty of experience arguing about how and when the 6d af system can be problematic. Bottom line is, if someone simply is out for denial, there are no ends of reasons to conjure up... so such a discussion is going nowhere anyway.

With the above comment, I just felt that a lighter mood was in order as the serial dr discussions do have a certain strange appeal, it's like a car wreck - you cannot stop yourself looking


----------



## heptagon (Nov 2, 2014)

Thanks for your post. A comparison with the 70D would be nice everything points towards that they have the same sensor.


----------



## jrista (Nov 2, 2014)

ajfotofilmagem said:


> Don Haines said:
> 
> 
> > ajfotofilmagem said:
> ...




I think that's a flawed assessment, though. It also paints everyone who wants more DR as raging egomainacs, which is absolutely not the case. I hope that Michael shares his full-size images, including the highlight areas, so that people can understand what these tests really do.If done properly, I expect the highlight steps of the wedge to be white. Only the top one should be pure white, the rest should be slightly less than pure white and barely differentiated. It might require some highlight recovery to properly demonstrate that (highlights are attenuated by RAW editors as well, to a small degree), but in the end, that's what the results should be. IF that is indeed the case, then the test was properly done, and the results have nothing to do with Michael trying to purposely bias the results or intentionally "underexpose". 


Cameras, including Canon's, have a lot more dynamic range than can be shown on a computer screen. The "bottom" several stops, the shadow stops (and the lowest "blacks" stop) very often contain data that in real life is not black, however those stops show up as black when the image is imported and displayed on a computer screen.


Why? Because with 8-bit rendering, you have 255 discrete tonal levels. You don't have 24 bits worth of tonal levels, you only have 8 bits, since it's the luminance range of each sub-pixel that ultimately matters here. In terms of stops, those 8 bits get you 20 * log(255/1) / 6, or 8.0218 stops. (There are some arguments that dithering can improve the dynamic range of a digital screen...possibly, but there is a lot of variation there, and it really depends on the screen...and empirically, it's easy to test how much dynamic range a computer screen has by, say, photographing a step wedge and seeing how many stops you have to lift the blacks before the bottom two wedges become a barely differentiated "pure black" and not quite so pure black.)


A Canon camera has around 11 stops or so, which means there are at least three stops of additional tonal detail that, rendered linearly, will just show up black or nearly black (in only 8 stops), when in real life it probably isn't. A camera with 13 stops of DR has at least five stops of additional tonal detail that, rendered linearly, will just show up black or nearly black. (This assumes you render linearly to display the highlights without clipping...most RAW editors actually render for the middle tones via a tone curve, with about a stop of recoverable shoulder in the highlights, and the rest in the shadows.)


Throw in the camera profile curves of a RAW processor (non-linear rendering), which attenuates the rendered signal, and all those near-blacks become fully black, and more tones become "shadow". Then you have the screen gamma, which further attenuates the signal, resulting in more information being rendered as black or nearly black.


Why do we lift shadows? To restore tones that, when rendered to screen, appear black on screen but in real life were not black and in the photo should not be black. That doesn't mean that every single tone in a rendered RAW image should be non-black, it just means that there can be stops...many stops in some cases...that should be non-black that, without shadow pushing, end up black in your photo. This isn't about anyone's dick being bigger than anyone else's. This is a fairly clinical subject...it's simple observations of data and results. 


Alright, I'm sure if I continue in this thread any longer, things will become a war (and a war not about a clinical subject...it'll get far more personal and hateful than that)...I don't want that. Michael, thanks for the test images. Interesting results. Looks like the 7D II definitely has less banding. Here's to hoping that Canon can improve their read noise in the next generation, and allow more of those shadow wedges to be usable in the future.


----------



## jrista (Nov 2, 2014)

Hmm...I am having strange problems with my posts. They end up with different font sizes and font faces, however I never mess with any of that. Apologies for the weird appearance of the prior post...wasn't my intention for it to render with different font sizes like that.


----------



## neuroanatomist (Nov 2, 2014)

jrista said:


> I just know that the resistance to and downright denial of the notion that improved DR matters, or that anyone is even remotely capable of performing a valid IQ test, or that Canon cameras might have a problem with anything, is extremely high here.





jrista said:


> I have no intention of playing any games. I said what I said, in the way that I said it, because I believe that is how a core group of members in this community...operate.



It seems you are flagrantly misrepresenting the viewpoint of that core group of members. Certainly, you're misrepresenting mine. If you're doing it knowingly, you _are_ playing games; if not, you're doing it out of ignorance or inaccurate memory. Either way, it's a misrepresentation. 

Would you like it stated that, "Jrista believes that Canon dSLRs suck," for example? That would be a misrepresentation, although perhaps not that far off given you did state that it can be _proven_ that Canon sensors deliver poor IQ.


----------



## AlanF (Nov 2, 2014)

heptagon said:


> Thanks for your post. A comparison with the 70D would be nice everything points towards that they have the same sensor.



Techradar has just added noise and resolution analysis to their review of the 7D II. They state that it has a different sensor from the 70D, with different microlenses. The 7D II has slightly better resolution at low ISO but the 70D catches up at higher. 

http://www.techradar.com/reviews/cameras-and-camcorders/cameras/digital-slrs-hybrids/canon-7d-mark-ii-1264977/review/4#articleContent


----------



## Marsu42 (Nov 2, 2014)

AlanF said:


> They state that it has a different sensor from the 70D, with different microlenses.



Nope, they state that _they have been told by Canon_ that yadaydayada 

I doubt tinkering around with the microlenses will make a big difference, reminds me of what they marketed on 5d2->5d3 and we know how much of a difference that made. Let's face it, it's a pimped Canon standard-ish crop sensor, either you're fine with "up to iso 1600" or you aren't.


----------



## Sporgon (Nov 2, 2014)

Marsu42 said:


> I doubt tinkering around with the microlenses will make a big difference, reminds me of what they marketed on 5d2->5d3 and we know how much of a difference that made.



No, the 5DIII has significant improvements over the 5DII, but they are subtleties that the philistonian user may not appreciate or recognise. 

Unlike an increase from 12 to 36 mp.


----------



## Perio (Nov 2, 2014)

Maybe it's just me but I'd be more interested in the comparison of AF speed and accuracy between 7dii and d750, as the latter apparently has very fast and accurate AF.


----------



## zlatko (Nov 2, 2014)

D750 has more DR? Good. I just don't care. Canon provides enough DR for everything I do, from weddings to portraits, and occasionally kids' sports. In every kind of light, in every kind of weather. Great results. More DR would be fine. A reason to switch? — not for me. The Canon system has too many other good things going for it.


----------



## MichaelTheMaven (Nov 2, 2014)

Perio said:


> Maybe it's just me but I'd be more interested in the comparison of AF speed and accuracy between 7dii and d750, as the latter apparently has very fast and accurate AF.



The focusing system on the D750 is not as good as the 5Diii in the head to head test I'll be publishing this week. 

I haven't tested the 7Dii the way I normally do, but my initial thoughts from shooting ~500 shots of windsurfers yesterday it is much better than both the 5Diii and D750. More cross types, (much) more AF point coverage. 

It was a LOT of fun to shoot sports action with it at 10 fps. 

The 7Dii sensor is different than the 70D sensor.


----------



## MichaelTheMaven (Nov 2, 2014)

jrista said:


> MichaelTheMaven said:
> 
> 
> > jrista said:
> ...



Thank you for your post. Im not here to start any fights with anyone about anything. 

The scrutiny in the past has actually been very beneficial and I have already learned that I was not clear enough in my description of what I am doing and was not effective in communicating how the test works. If I am not "impossible to misunderstand" in what I am doing, then I am at fault with what I am presenting and need to re-evaluate how to improve it. 

What is the best way to share RAW files on here? They are kinda big.


----------



## jrista (Nov 3, 2014)

I share RAWs with Microsoft OneDrive myself. I'd say any of the online storage solutions offer enough space to share a handful of RAW images.


----------



## neuroanatomist (Nov 3, 2014)

zlatko said:


> D750 has more DR? Good. I just don't care. Canon provides enough DR for everything I do, from weddings to portraits, and occasionally kids' sports. In every kind of light, in every kind of weather. Great results. More DR would be fine. A reason to switch? — not for me. The Canon system has too many other good things going for it.



You hereby stand accused of the heinous crime of heresy against the Holy Exmor. How can you fail to comprehend the glory of the Holy Exmor, which by its very existence rendereth the IQ of your Canon sensor so poor as to be unacceptable to all the right-thinking. Prepare to be burned at the stake at midnight. 

Sadly, the pathetic Canon cameras lack sufficient DR to capture the highlights of the flames and the shadows of the surroundings, and should your heathen brethren attempt lifting the shadows 4 stops to see the identity of the onlookers' faces, their efforts will be futile due the horrendous noise.


----------



## AlanF (Nov 3, 2014)

MichaelTheMaven said:


> Perio said:
> 
> 
> > Maybe it's just me but I'd be more interested in the comparison of AF speed and accuracy between 7dii and d750, as the latter apparently has very fast and accurate AF.
> ...


If the 7DII's focussing is much better than that of the 5DIII then it must be truly remarkable.


----------



## Don Haines (Nov 3, 2014)

ajfotofilmagem said:


> Don Haines said:
> 
> 
> > ajfotofilmagem said:
> ...


Quite true, but the OP's second sentence was "I know it is an Apples to Oranges comparison, but I was curious none-the-less", which I took to mean that this was not a very scientific test.... As most of us can't properly process the RAW files yet, I think proper tests are a long ways away....


----------



## jrista (Nov 3, 2014)

Don Haines said:


> As most of us can't properly process the RAW files yet, I think proper tests are a long ways away....




Hmm...doesn't Canon's DPP 4.1 support "proper" processing of 7D II raws? We may not have official Lightroom support, or Capture One support, etc...but I think it would be a bit of a blunder if Canon released a camera and did not give their customers the ability to edit the RAW files...that doesn't sound like them...


----------



## Woody (Nov 3, 2014)

jrista said:


> Hmm...doesn't Canon's DPP 4.1 support "proper" processing of 7D II raws? We may not have official Lightroom support, or Capture One support, etc...but I think it would be a bit of a blunder if Canon released a camera and did not give their customers the ability to edit the RAW files...that doesn't sound like them...



I believe even DPP 4.0.1 supports 7D2.

The issue is that DPP can only be used to process Canon RAW files.

It probably makes more sense to use a common software e.g., Lightroom that can handle RAW files from different manufacturers. I believe this is what DPReview does.

Also, DPP output is different from Lightroom. I converted Imaging Resource 70D RAW using DPP and LR. Even with all NR sliders turned to zero, DPP has less noise than LR. Image details appear similar to me.


----------



## Don Haines (Nov 3, 2014)

jrista said:


> Don Haines said:
> 
> 
> > As most of us can't properly process the RAW files yet, I think proper tests are a long ways away....
> ...


If we were going to go crazy about controlling variables for a comparison test, we would use the same software program at the same settings to generate our images..... We can't do that yet with 7D2 files. I am fairly willing to bet that in a few weeks that problem will be solved.....


----------



## aardvark (Nov 3, 2014)

AlanF said:


> heptagon said:
> 
> 
> > Thanks for your post. A comparison with the 70D would be nice everything points towards that they have the same sensor.
> ...



Note that the article doesn't say its a different sensor - it says ""A new sensor and processing engine combination, along with advanced metering and AF systems" which given the dual digic processors used haven't been used with a 20.2 sensor is clearly true. I am not aware of any articles absolutely stating the sensor is different to the 70D ...unless I missed something. Also it states it has different micro lenses and new device, but 70d sensor plus new micro lens = new device? Depends what you define as the sensor I guess

I guess the point is that they aren't being very open about this so you wonder, and this article is just really a re-write of what we already know so doesn't really help.

Why is this important? Well if your not worried about much better AF and other great features on the MKii then you can buy a 70D for a lot less! Also I guess it matters because it potentially shows canon's slow progress in this area if its just a tweak of the 70d. However, there are other reviews from well known figures (all beit tied to canon) that state its sensor performance is a significant step up!


----------



## MichaelTheMaven (Nov 5, 2014)

As promised, here are the Dynamic Range Test Shots I took. I redid the entire test, with more cameras, including:

- Canon 7DII
- Canon 7D
- Canon 5Dii
- Canon 5Diii
- Canon 70D
- Sony A7s (Not Slog)
- Panasonic GH4
- Nikon D750

For each of the images I am clipping out the 1st step of the wedge, leaving the other 40 or so for analysis, this overexposure is recoverable in RAW files, so Ive also included a screen shot of what I am doing in Camera Raw with the sliders. 

Let me know what feedback you guys might have on how I can improve it. https://www.hightail.com/download/UlRTaklncG9tMEpBSXNUQw

Best wishes

Michael


----------



## privatebydesign (Nov 5, 2014)

Thanks for the upload.

I am still seeing uneven lighting, you have dramatic fall off after number 38. 

I am not suggesting you are slanting the test to favour any camera, just that you have a methodology issue.

Also, I am not getting clipping on the first step, some are 245 ish, not 255, I don't see how you can lift exposure and shadows in post and expect even results either. 

When I did similar tests on film and paper you had to take a series of images with different exposures and select the one that gave you a clipped step 1, then you can see where the darkest tone still is, without adjustments.

Otherwise you could do this, it is the 70D adjusted from your one shot to show clipped blacks only in step 41 and clipped whites only in step 1, or the full DR of the wedge!

I think that to demonstrate what you are trying to you need to make different exposures with each camera, you need to get the light even so all the step numbers are the same values (that is why they are like that), you need to compare the one exposure from each camera that clips step 1 then look at the shadows. If you run into screen DR limitations you need to look at brighter exposed images and count the difference in EV between them to arrive at the sensor DR capabilities.


----------



## MichaelTheMaven (Nov 5, 2014)

A few comments- 

The actual numbers on the the strip are all the same as step 1, *with the exception of the last 3-4*, these are different for some reason (the numbers themselves are actually darker- I do not know why). Number 41 is so dark, that without a special light, you cannot see it (it just looks black). 38, 39, 40 are increasingly dark as well. It might have something to do with the process the strip is meant to be used for. IDK. 

The lighting set up positions were the same in all tests, double diffused, constant coverage and larger than the target area itself. I wouldn't know how to get it more even than it is. 

This second time around, because there were so many cameras involved, there were some micro adjustments required on the light power itself, especially the GH4, who's iso only goes down to 200, not 100, so that had to be adjusted to compensate for the ISO change.

Still, my thought is clipping out the 1st step on every camera (which you can see it with highlight alert), that would be a calibration point for the rest of the 40 steps. Importing RAW files, obviously this is recoverable, which means there is still some head room and why I don't think it is a good test for total DR. Also, there were no strobe power adjustment changes between the D750 and 5Diii, and that wouldn't explain the differences in performance there. 

I tried bracketing, the problem there becomes that we are using a 13.7 EV strip, once you burn off 4-5 stops, you only have 8-9 to analyze, so I my goal was to squeeze it down to the first step as a way to try to calibrate each cameras start point for the test. 

Ultimately, I think the way to do it is with a 15-20 stop strip, but the only test I know of that works in that range is $3,500.

I appreciate the comments and feedback. Im listening. Im learning that I need work on how I present my methodology as well as why I did the test a certain way.


----------



## msm (Nov 5, 2014)

Michael, I checked you files with RawDigger and even the first step seems to be quite a bit lower than clipped on more or less all your files. Raw converters give highlight warnings when the converted jpg clips, not when the rawfile clips so there is often much more highlight headroom in the rawfiles than one would think.

In order to get better control over the potentional of your raw files, you may be interested in checking out RawDigger at (free 30day trial):
http://www.rawdigger.com/


----------



## Lawliet (Nov 5, 2014)

MichaelTheMaven said:


> I appreciate the comments and feedback.



As a secondary observation: Watching not only for the borders between steps, but even on clearly delineated steps for color uniformity is interesting - if it gets too colorful here on should netter expect either a similar effect or heavyhanded noise reduction on areas in the same zone of production pictures.


----------



## MichaelTheMaven (Nov 6, 2014)

Lawliet said:


> MichaelTheMaven said:
> 
> 
> > I appreciate the comments and feedback.
> ...



This is very excellent input. (about the actual tones from 2 side-by side swatches) I wonder what a good way to determine specifically at what point that happens. Some of the swatches look identical to me in the mid 20's, but it does seem there is a point that noise kinda starts messing everything up after a certain point. 

Another thing you guys helped me realize, is that the exposure slider amount (which is in EV) to the point at which the first step clips out, minus that one step of over exposure, might be useable to calculate total DR. There is some headroom on the bright end, and if we are clipping out the first step, wouldn't it be the amount we moved that slider over in camera raw? Almost seems too obvious to be believable.


----------



## jrista (Nov 10, 2014)

I just thought I would share some info on the raw files Micheal shared. I decided to load them up in PixInsight. PixInsight is an astrophotography processing tool, and it is extremely powerful. It has amazing tools, many for noise reduction. It also has a statistics module as well. The cool thing about PI is you can operate on your images in linear space (without any additional processing applied, so it's "pure", untainted data that has not been affected by RAW editor tone curves or anything like that.) It is also capable of processing data in a wide variety of numerical spaces, including 8/10/12/14/16-bit integer, 32-bit float as well as 64-bit float. So, it makes for a nice platform for analyzing data in an objective manner. 


To that end, here is some data I was able to generate using PI's statistics module in linear mode, with the original images without any edits, as well as some after various attempts at noise reduction. I used a PixInsight feature, Previews, to cordon off certain regions of each image and perform statistics on. Most of the statistics I'll be providing will have a name in the form of <imageFile> -> <previewName>, just so you know what your looking at.


First off, the linear images, when opened up in PI, definitely show that swatch 1 was not anywhere close to the clipping point, in either image. Here are a couple crops showing just the strip, as rendered by default in PI's linear mode, along with statistical details from swatch #1:


5DIII







_3H7C0105->Preview04
Data Point R G B
*count (%)* 100.0000 100.0000 100.0000
*count (px) * 63784 63784 63784
*mean * 166.227 154.809 177.034
*median * 165.973 154.607 176.774
*variance * 46.421 31.791 38.432
*stdDev * 6.813 5.638 6.199
*avgDev * 7.068 5.867 6.444
*MAD * 7.609 6.328 6.951
*minimum * 135.272  131.047 147.743
*maximum * 191.163 175.872 201.148




D750






DSC_1424->Preview06
Data Point R G B
*count (%)* 100.0000 100.0000 100.0000
*count (px)* 62748 62748 62748
*mean * 191.694 172.764 185.102
*median * 189.837 171.012 183.233
*variance * 58.980 43.680 44.843
*stdDev * 7.680 6.609 6.696
*avgDev * 7.971 6.870 6.953
*MAD * 8.065 6.738 6.738
*minimum * 176.241 158.728 167.611
*maximum * 218.949 194.171 205.922


The statistics are for each color channel, so R,G, B. As you can see from the maximum data point, the white level, it barely topped 200 levels (8-bit), meaning there was really a TON of headroom left on each sensor. This explains why the swatches became indiscernible from each somewhere between swatch 17 and 22, when I expected them to remain visible beyond that. 

To clarify what's going on here. I know that swatch 1 appeared to be "clipped" to Michael. Both the cameras themselves, and any RAW editor he would have used, would have shown the white swatch #1 to be nearly or actually pure white because of tone curves. PixInsight does not apply any kind of curve unless I tell it to, so the images I've shared above are truly, 100% linear space. 

As a side note...you should notice that the D750 crop is more reddish, and appears a bit brighter. It seems the red channel is slightly brighter in this image. I am not sure why, possibly a difference in white balance. The D750 image is indeed exposed a little bit more than the 5D III image. Again, if you look at the maximum statistic, you can see that there is a difference of ~30 levels in red, ~20 levels green, ~5 levels blue. Such a discrepancy should be eliminated for the most objective test results. I would say that swatch #1 should be clipped, all levels should be 255, 255, 255. Swatch 2 should be as close as possible to clipping without actually clipping in any channel, and the channels should deviate as minimally as possible (both across channels and across cameras...so if you get something like 250, 250, 250 +/- 3 in both cameras, that should suffice.) 



This may be an opportunity to further explain, with a visual backup, something I've tried to explain in the past about shadow pushing. Note how much of each swatch, regardless of whether it is the 5D III or D750, is black? I don't just mean dark, but black. To my eyes, with my screen brightness turned up to maximum, in linear space, I could not differentiate any swatches from 22 through 41 for the D750, and I could not differentiate swatches 17 through 41 for the 5D III. That means that, in the case of both cameras, half or more of the dynamic range by default renders as black on screen. It isn't actually black, as you'll see in a moment here when I "stretch" the data, there is a lot of tonal detail in those "black" swatches that are most definitely not black. It just looks black. That is why we push shadows. 

(Caveat: Since the highlight swatches were underexposed, once properly lit I suspect that the "indistinguishable from black" zone would shift down to swatches 25-29 or around there...however even in that case, one solid third of the tonal range available in the Stouffer T4110 step wedge shows up black by default, and this some of it (not necessarily all of it) would need to be pushed in order to contribute usefully to the final photograph...and this is even more true with a standard S-type contrast curve applied...that would again darken some of those swatches, maybe bringing the range back to somewhere between 22-25.)



Anyway, moving on. The next set of statistics are from the same linear images as shown above. Only in this case, the statistics are from swatch 41. There are two interesting things I glean from these statistics: noise levels and maximum level. I've also included a couple more images. These images demonstrate PixInsights "screen stretch" function, which applies a default MTF stretch curve to bring up the deep tones. The white swatches get blown, however screen stretch is normally intended for use with astro images, which pretty much don't have "whites"...almost all the data in an astro image falls into swatches 39-41.  Anyway, the screen stretch aims to bring up the darkest tones to a common level, and it is fully automated (in other words, I did not do anything personally to bias the results), so it is a good visual indication of the differences between each camera.


5D III






_3H7C0105->Preview01
R G B
count (%) 92.3782 95.3265 91.3499
count (px) 18956 19561 18745
mean 0.282 0.178 0.170
median 0.261 0.167 0.163
variance 0.026 0.007 0.010
stdDev 0.163 0.085 0.100
avgDev 0.160 0.081 0.098
MAD 0.156 0.081 0.098
minimum 0.008 0.008 0.004

maximum 1.268 0.642 0.825


D750






DSC_1424->Preview01
R G B
count (%) 100.0000 100.0000 100.0000
count (px) 23896 23896 23896
mean 19.070 9.470 10.899
median 19.074 9.471 10.899
variance 0.001 0.000 0.001
stdDev 0.038 0.019 0.023
avgDev 0.037 0.019 0.021
MAD 0.035 0.012 0.017
minimum 18.895 9.370 10.794

maximum 19.241 9.572 11.027


So, first statistic, *maximum*. There is clearly a large difference between the two cameras here. At this level, despite the D750 being slightly more exposed than the 5D III, a difference in maximum level of 10-20 levels is FAR more meaningful than a difference of 20-30 levels in the highlights. I honestly do not know if this is simply because the D750 has more dynamic range or not. Whatever the cause, the difference in maximum level between the 5D III and D750 here is massive. More massive than I would have assumed given the exposure levels of both cameras. I would be very, very interested in seeing what changes here if the exposures were fixed (i.e. Step 1 fully clipped, step 2 close to but not actually clipped.) I suspect the 5D III maximum level would increase, but so would the D750 maximum level. Would they deviate even more? Interesting stuff. (Michael, do you think you could rerun the D750, 5D III, and 7D II step wedge tests to correct the exposures?) 


Second statistic, *stdDev*. This is the noise level, the standard deviation from the mean. It is about an order of magnitude difference in the green channel, more than an order of magnitude difference in the red and blue channels. I think the numbers speak for themselves...the D750 has significantly lower noise than the 5D III. I don't think anyone should be surprised by that...however I do think it is quite telling, as it can explain why the D750 steps from 35-41 look so clean...there is very low noise. 


As far as the darkest steps with a discernible edge. With the screen stretch, I can see an edge between 35/36 on the 5D III, and I can see an edge between 37/38 on the D750. Because I was curious, I threw in some previews on swatch 41 of the stretched versions of both images, and here are the stdDev and maximums for each:


5D III
_3H7C0105_clone->Preview01
mean 59.503 59.127 55.742
median 59.735 58.634 56.661
variance 699.516 478.584 642.829
stdDev 26.448 21.877 25.354
maximum 152.770 136.280 150.739


D750
DSC_1424_clone->Preview01
mean 58.039 54.884 54.096
median 58.082 54.366 53.284
stdDev 11.211 6.536 6.822
maximum 97.654 84.568 87.623


Again, I think the statistics speak for themselves. Very similar mean/median values for both swatches (screen stretch aims to achieve a normative result, so we should expect that both images would have the same mean), big difference in stdDev and maximums (the higher stdDev of the 5D III ultimately pushes the brightest pixels brighter than on the D750...that IS what noise is, the deviation around the mean, and the larger the deviation, the brighter the brightest pixels will be.)





Finally, I ran some noise reduction on both sets of images. PixInsight has some phenomenal NR tools. One of my favorite is TGVDenoise. This is a Total Generalized Variation algorithm, and makes use of a slightly different kind of math to effectively wipe out noise entirely to a certain frequency, while generally leaving lower frequencies untouched. It is very good at removing per-pixel noise frequencies, without affecting lower frequencies at all.

I've applied TGVDenoise to the two images below, then stretched them with a screen stretch so you could see the results:


5D III






D750






TGV is configured according to the statistics of each image. I used the same settings for both images, with the exception of the Edge Protection setting, which I configured according to the stdDev statistic. By doing this, the same frequencies of noise are removed from each image, leaving behind the rest. I believe the results are once again pretty self explanatory. Aside from the vertical banding, there is clearly some other level of lower frequency noise present in the 5D III image. I personally refer to this as color blotchiness. Even despite the complete obliteration of high frequency noise, it doesn't really change things for the 5D III...the color noise is still very intrusive.


For a little bit of subjective opinion, as far as the first swatch where noise becomes unacceptably intrusive, without any NR, I wold say swatch 25 on the 5D III. On the D750, it isn't particularly objectionable to me all the way to swatch 41, but if I had to pick an eminently usable cutoff point, I'd say around swatch 32 or 33. With NR, I would say swatch 27 on the 5D III, and swatch 37 on the D750. 



One final thing. I thought it would be useful to show an example of what I think a properly exposed step wedge should look like rendered as unprocessed linear data. Michael, if you do generate some additional images, I think you should aim for something like this:


----------



## Marsu42 (Nov 10, 2014)

jrista said:


> To clarify what's going on here. I know that swatch 1 appeared to be "clipped" to Michael. Both the cameras themselves, and any RAW editor he would have used, would have shown the white swatch #1 to be nearly or actually pure white because of tone curves. PixInsight does not apply any kind of curve unless I tell it to, so the images I've shared above are truly, 100% linear space.



I had already read about "linear in the Photomatrix help as they've got a checkbox "import linear source file" and say that this doesn't apply to converted raw files. I admit I didn't really understand it, but I take it this means that setting the tone curve to "linear" in ACR/Lightroom still applies processing? How's that - behind the scenes or with the calibration profiles?


----------



## jrista (Nov 10, 2014)

Marsu42 said:


> jrista said:
> 
> 
> > To clarify what's going on here. I know that swatch 1 appeared to be "clipped" to Michael. Both the cameras themselves, and any RAW editor he would have used, would have shown the white swatch #1 to be nearly or actually pure white because of tone curves. PixInsight does not apply any kind of curve unless I tell it to, so the images I've shared above are truly, 100% linear space.
> ...




Most RAW editors apply a default set of tone curves. In the case of ACR/LR, yes, it's the calibration profiles. A "linear" tone curve applied to any RAW image opened in ACR/LR is still going to have those base calibration profile curves applied, as they are (as far as I know) applied as part of the demosaicing process. When I used Aperture in the past, it was pretty much the same thing, as does RawThearapy. I think DarkTable may have a linear mode...haven't used that much. 


The only tools that I know that will open RAW files in true linear space are PixInsight, and a free astro editor called Iris. Iris is ok, very limited. PixInsight is by far the best linear space editing tool I've ever come across.


----------



## Woody (Nov 10, 2014)

From Thom Hogan, a Nikon supporter for decades...

http://www.dslrbodies.com/newsviews/do-you-believe-in-dxomark.html

"...The DxOMark Overall Score is one of those faux statistics that attempt to put a lot of test data together with a lot of assumptions and come up with a single representative numeric value....

I’ve written before how the digital camera world has basically followed the old high fidelity world in terms of numbers-oriented marketing and testing. Back in the 70’s and 80’s people got crazy about frequency or power ratings for high fi gear. Yet in the long run, people who listened to the products found that slavish devotion to buying better numbers didn’t actually get them “better sound.” ...

It’s interesting to note that DxO seems to be playing a lot of angles. First, they are presenting themselves as impartial, numeric oriented testers (e.g. the scores). Second, they are presenting themselves as reviewers (e.g. "If Canon could only address performance at base and low ISO, the EOS 7D Mk II would make a thoroughly convincing all-round choice, but in this category the Sony A77 II looks to be the more compelling option."). *Third, they sell their test equipment and software test suites to camera companies (Nikon, for instance, but I don’t believe Canon is one of their clients)*. Fourth, they present themselves as the best demosaic option, better than the camera makers’ options (e.g., DxO Optics Pro). They have some clear conflicts of interests that are not easily resolved. So be careful of just gobbling up their “results” as absolutes...

Even though those DxO-reported numbers aren’t what I’d expect in my images, they do tell me something: I might be able to dig more shadow detail out of the D7100 image than the 7DII image at base ISO, all else equal. That’s actually no surprise. This has been true of the Sony versus Canon sensor difference for quite some time now. If you’re a big fan of cranking the Lightroom Shadow slider to max, you’re going to be doing more noise correction on a Canon than a Nikon. Nothing’s changed here. However I’d point out that neither camera is likely to be able to hold extreme landscape situations in a single exposure: I’d still be bracketing and applying HDR type techniques to construct images in such cases. Thus, whatever the actual numeric difference in dynamic range between the 7DII and D7100 is at base ISO, it really wouldn’t make much of a difference to my workflow. I might adjust my bracket sets on the Canon to be a bit different than the Nikon to account for the difference in how they handle shadows, but that’s it. Bottom line, I’d get the same image."


----------



## nda (Nov 10, 2014)

Very interesting jrista... You should email this data to a tech head at canon japan hq :'(.


----------



## MichaelTheMaven (Nov 13, 2014)

Jrista- hey I wanted to thank you for taking the time to put that all together, I really appreciate it. Your comments and several others have really helped me with presenting this information in a much cleaner way. 

Im a bit short on time right now, but I will do more DR tests in the future.

I have taken many different exposures (bracketed) and what happens is when clip out in the RAW file as it is opened, I don't have enough swatches on the strip to get a good reading. 

Additionally, even at the same exposure settings and flash power, some cameras still exposure slightly differently, I see it all the time in side by side shooting. 

I am very curious about the software you mention, is anything you are aware of that can measure the signal to noise ratio of a specific swatch? Maybe cropped? I have some ideas, but it would be easier to measure a specific swatch.

Im still curious if it would be reasonable to add the total Exposure Slider value (in this case 2.0) if my me more serves me correctly, to the swatch reading (lets say 32-33, would be 10.67EV, or 12.67 ev, minus the one over exposed swatch, for a total of 12.33EV.? If we could precisely measure the signal to noise ratio threshold on both swatches instead of eyeballing it, it could very well be a cheap and easy way to at least estimate the ball park DR. 

BTW- the Epic Shootout on the D750 and 5Diii posted last night, thought I would share it with you here. Again, thank you guys for your help in clarifying what / how I was presenting it. 

http://youtu.be/EsZtUZvoeO0


----------



## jrista (Nov 13, 2014)

MichaelTheMaven said:


> Jrista- hey I wanted to thank you for taking the time to put that all together, I really appreciate it. Your comments and several others have really helped me with presenting this information in a much cleaner way.




You are very welcome.



MichaelTheMaven said:


> I have taken many different exposures (bracketed) and what happens is when clip out in the RAW file as it is opened, I don't have enough swatches on the strip to get a good reading.
> 
> Additionally, even at the same exposure settings and flash power, some cameras still exposure slightly differently, I see it all the time in side by side shooting.




When you say "get a good reading"...with what?



MichaelTheMaven said:


> I am very curious about the software you mention, is anything you are aware of that can measure the signal to noise ratio of a specific swatch? Maybe cropped? I have some ideas, but it would be easier to measure a specific swatch.




I was measuring on specific swatches. What I did in PixInsight is draw previews around the center part of individual swatches. In the Statistics tool, I can select any one of those previews, and get SNR and other details just for that one swatch. It's very useful.




MichaelTheMaven said:


> Im still curious if it would be reasonable to add the total Exposure Slider value (in this case 2.0) if my me more serves me correctly, to the swatch reading (lets say 32-33, would be 10.67EV, or 12.67 ev, minus the one over exposed swatch, for a total of 12.33EV.? If we could precisely measure the signal to noise ratio threshold on both swatches instead of eyeballing it, it could very well be a cheap and easy way to at least estimate the ball park DR.




I would need to know more about how your getting the DR readings. Adding exposure is not the right way...that is a modification after the fact, so you are not getting a valid DR reading of the camera. You really do need to expose Swatch #1 up to the point of clipping (maybe not fully clipped, but just to the point where it begins to clip). Otherwise, you are throwing away dynamic range, and more darker swatches will be buried in the read noise. 


If your underexposing swatch 1...and, based on my analysis, your currently underexposing it A LOT, I mean, a LOT LOT, way too much since the levels are ~200 in 8-bit, which means you are throwing away ~55 levels, or over 21% of the signal space. Your throwing away DR. Or in other words, you are not actually measuring the full dynamic range of *the sensor*.



The key here is to expose as close to the limit as possible, so that fewer dark swatches become "dominated by noise", or close to that 1:1 SNR, where it doesn't really matter how much NR you do (and, I spent a lot of time trying to figure out a way of recovering the noise-ridden swatches from the 5D III image, the ones where you couldn't see the seam between swatches...there simply isn't any way as far as I can tell...nothing in PixInsight and none of my NR tools in PS, including Topaz and Nik...could recover anything useful below, what was it, swatch 35?)


I don't think that is going to change the results. Not much. The 5D III may gain one swatch on the D750...but the D750, which already demonstrates great performance right down to swatch 41, is going to get better as well once you push swatch 1 to clipping.


----------



## MichaelTheMaven (Nov 13, 2014)

*When you say "get a good reading"...with what?*

For example, if I clip out on the D750 in RAW, the swatch itself only has another 13.3 stops left to analyze. If a cameras DR is 14 or more, we wouldn't be able to see it because of the limit of the strip.

When you suggest clipping out that first swatch, what that means is there won't be enough room on the remaining part of it. They don't make a strip with anything more. Ill think about this. 4 stop ND filter in front of a portion of it perhaps? 

Ill have to check out that software in that case. Thank you again!


----------



## jrista (Nov 13, 2014)

MichaelTheMaven said:


> *When you say "get a good reading"...with what?*
> 
> For example, if I clip out on the D750 in RAW, the swatch itself only has another 13.3 stops left to analyze. If a cameras DR is 14 or more, we wouldn't be able to see it because of the limit of the strip.




That's ok. I understand the limitations of the Souffer strip. What I am saying is, if you do not...overexpose, swatch 1, then your not actually able to measure the true DR of the camera. Tight now, swatch one is being exposed about 21% or more below the point where it "clips out" (see below...I think there is just a misunderstanding of this term). If the D750 has, what, 13.8 stops, then at best, if we got the necessary statistics (which I think we have, I'll have to see about actually calculating the DR for real), then I would say at best, the data would show only around 11 stops for the D750, and maybe 9 stops at best, if that, for the 5D III. Because the highlight levels stop 21% below the _digital clipping _point...levels 201 through 255 are not being used...so your effectively throwing them away in your test. 


Does that make sense? I can try to think of a better way of explaining...



MichaelTheMaven said:


> When you suggest clipping out that first swatch, what that means is there won't be enough room on the remaining part of it. They don't make a strip with anything more. Ill think about this. 4 stop ND filter in front of a portion of it perhaps?




No, I think your just misunderstanding, and that is probably my fault for not explaining properly. I don't mean actually, say with scissors, "clip" off any part of the chart.  I mean, expose it enough that the digital values "clip"...in this context, the word clip means that you have exposed enough that the highlight values in swatch one need to be say 257, 258, 260...but the numeric space only allows you to go up to 255. When you need numbers that are outside of the available numeric space, the technical term for what happens to them, they end up being the maximum allowed value of 255 instead of 257, 258, 260, is that those values are "clipped". It's a virtual thing, a numbers and math thing, not a physical thing.  


I will see if I can demonstrate better when I get home. Basically, right now, your not using all of the strip. I'm trying to say, there is more room (digitally, in terms of number space, not anything physical) on the strip than you are using so far, *because *your _not '_clipping' (or ever so slightly over-exposing) swatch 1. I don't mean you have to clip it heavily...you just need to get the levels in that swatch to say between 253-255 (and some will probably be brighter than that, hence why they are "clipped"). Once you get to that point, _then _you will fully be utilizing the entire strip properly.


----------



## MichaelTheMaven (Nov 13, 2014)

Im glad someone finally realizes that it isn't quite as straightforward as it should be. Ultimately, the ideal solution would be to have a 15 stop strip. My understanding of what I am doing now, is yes, I am throwing away the first part of the DR test because we pretty much know what it should look like, an over exposed first step, a few not over exposed and so on, and what we are doing is looking at the last 80% or so of it to try to measure its end performance. (We are throwing away about 2 stops if we are going the slider route, which I see you do not agree with). 

Im all ears if you think there is a way we can do it better than this. 

Thank you for your time


----------



## DominoDude (Nov 13, 2014)

MichaelTheMaven said:


> Im glad someone finally realizes that it isn't quite as straightforward as it should be. Ultimately, the ideal solution would be to have a 15 stop strip. My understanding of what I am doing now, is yes, I am throwing away the first part of the DR test because we pretty much know what it should look like, an over exposed first step, a few not over exposed and so on, and what we are doing is looking at the last 80% or so of it to try to measure its end performance. (We are throwing away about 2 stops if we are going the slider route, which I see you do not agree with).
> 
> Im all ears if you think there is a way we can do it better than this.
> 
> Thank you for your time



As I see it it's not about "throwing away". To calibrate the exposure the first strip needs to show up as fully saturated in all colour channels (R=255, G=255, B=255) - this is what's called clipping.


----------



## MichaelTheMaven (Nov 14, 2014)

Looks like we will disagree on this. It is kinda hard to measure supposedly 14.5 stops of DR on a 13.7 strip, with really 13.3 EV to work with. The way I see it, the slider does allow us to recalibrate the analysis, clipping the first point off starting from 2 stops in, Id love to understand why that is an unreasonable assumption. Add that two stops back in after the calculation and both cameras are well within the ballpark of much more expensive methods. 

Again, if you have a better suggestion I am all ears.


----------



## jrista (Nov 14, 2014)

MichaelTheMaven said:


> Looks like we will disagree on this. It is kinda hard to measure supposedly 14.5 stops of DR on a 13.7 strip, with really 13.3 EV to work with. The way I see it, the slider does allow us to recalibrate the analysis, clipping the first point off starting from 2 stops in, Id love to understand why that is an unreasonable assumption. Add that two stops back in after the calculation and both cameras are well within the ballpark of much more expensive methods.
> 
> Again, if you have a better suggestion I am all ears.




It is not a disagreement, Michael. I don't mean to be rude, so with all due respect, you are misunderstanding how to use the strip. You don't need 14.5 stops, because you are not even making full use of the 13.7 stops the strip you have now currently offers. Until you clip swatch 1, you are under-utilizing the Souffer 4110 Wedge. It isn't a matter of opinion here, it is a matter of proper application. It is necessary to clip that first stop. The rest is a simple matter of mathematics.


I checked out the statistics in PI, calibrated to 14-bit. In 14-bit number space, the Max (Swatch 1) and STDev (Swatch 36/40) values are:


5D III (Red): 12282/10.5
D750 (Red): 13644/2.5


5D III (Green): 11300/5.8
D750 (Green): 12144/1.3


5D III (Blue): 12923/7.5
D750 (Blue): 12941/1.5


In terms of dynamic range, the formula when using digital numbers is 10 * log(Max/Stdev) * 3 (similar but slightly different to the formula when using electron charge) , which takes the maximum (saturation) over the standard deviation of noise (of a swatch where SNR reaches a ratio of ~1:1...I used the first swatch where the seam between it and the next swatch was not visible in each image, as every swatch after that looked the same (for some reason the PI statistics window doesn't actually directly report SNR, so this was my only real option)...this was swatch 36 for the 5D III, swatch 40 for the D750). I ran the above formula, and got the following:


5D III (Red): 10.22 stops
D750 (Red): 12.45 stops


5D III (Green): 10.96 stops
D750 (Green): 13.23 stops


5D III (Blue): 10.78 stops
D750 (Blue): 13.12 stops


The red channel in the D750 image is exposed a little bit more than the other two channels, and that seems to weight the noise, hence the reason that channel has 12.45 stops instead of 13.something. These numbers seem to be pretty in line with what I was expecting, given the exposure level of swatch 1 in both images. 


To actually reach 13.7 stops of dynamic range, we need the maximum level to be 2^14 - offset. In a Canon camera, the bias offset is 2048. In a Nikon camera, the clipping offset is 600 (this is based on work by some guys at Nikon Hacker who figured out how to restore a bias offset to Nikon cameras for astrophotography purposes, which after the black point clipping was removed, resulted in a bias offset of 600). So, for the 5D III, the maximum level that can be reached in a given pixel is 14366. For the D750, it is 15784. At those levels, to reach 13.7 stops of DR, you would have to have read noise as low as 1.113 for the 5D III (not going to happen), and 1.23 for the D750 (well, it got as low as 1.3 in the green channel...so, maybe.)


Anyway, if we run the math with those numbers:


5D III (Max Stouffer DR): 10 * log(14366/1.11) * 3 = 13.7067 stops
D750 (Max Stouffer DR): 10 * log(15784/1.23) * 3 = 13.69437 stops


With maximum saturation numbers like 12282 and 13644, you are exposing WELL below the clipping point on swatch 1. Swatch 1 needs to be clipped, then swatch 2 would be used as the maximum saturation swatch, and whichever the first swatch where the seam between it and the next becomes invisible would be used for the standard deviation (SNR 1:1) swatch (this, at least, is the only way it could be done using PI statistics...I am honestly not sure which swatch is truly where SNR 1:1 would first occur...but I don't have any better way at the moment given the tools at my disposal, and once all the dark swatches reach a point where they all look the same and blend into each other, you HAVE reached the minimum usable level.). That is the only way to properly use the Stouffer T4110 Step Wedge. _Otherwise you are under-utilizing it._ 


Based on the numbers above, your about two thirds of a stop or so under-exposed, which is fairly significant.


----------



## MichaelTheMaven (Nov 14, 2014)

My last post directed at Domino Dude. Not you Jrista. 8) you know it might be easier for you to get a wedge and try it out, they are only $14.


----------



## jrista (Nov 14, 2014)

MichaelTheMaven said:


> My last post directed at Domino Dude. Not you Jrista. 8)




Right, but...he was correct. ;P And I was also responding to what you were saying about needing 14.5 stops. You don't, your current wedge has plenty of space to handle what were saying you should try doing to make proper use of the wedge and get accurate dynamic range readings.


Oh, another thing. The 14.5 stops...I haven't checked, but I assume that is what DXO is reporting as the D750's dynamic range? That is incorrect. That is the NORMALIZED dynamic range. The "Print DR" as they call it. You should be referencing their Screen DR numbers instead, since your images are 100% full size. You are not downsampling them (and neither have I been in my analyses in PI), so Screen DR is the only number reported by DXO that is going to accurately represent the "hardware DR", or the DR of a non-scaled RAW image. I am trying to check DXO now, but their site is mind-bogglingly slow, and isn't loading the page. I assume that the Screen DR is less than 14.0...as mathematically it is impossible to have more than 14 stops of DR with 14-bit data. I suspect it is somewhere between 13.5 and 13.8 stops Screen DR, in which case, your wedge has just about enough space to accurately measure the dynamic range of the D750.


----------



## MichaelTheMaven (Nov 14, 2014)

Then we are going to have to respectfully disagree. If the precision your require is as outline, you cannot measure anything over 13.3 DR with a just a 13.3Ev strip. I would be happy to buy you an ND strip if you believe you can work it out. 

I can see you are putting a lot of analysis into this and I really appreciate it. We agree on many points about the utilization of the wedge, but I actually think there are several ways to use it (not just one) and possibly even better tests that will come from it. Right now I am leaning towards putting a 4 stop ND filter infront of it, which technically then could get us a strip in the 17 Stop range. 

Additionally, what you are suggesting to overexpose the first step and only that first step on all cameras, as well as all channels is going to be just about impossible, and would make the test less quick and easy and more of a headache. 

My mind still isn't reconciled that what I am doing is incorrect for comparison between two cameras shooting on the same settings, so we might disagree there too and that is ok.

I think the results are easily visible and speak for themselves and I am still open to any feedback you or others have and definitely do not want my gratitude to be misinterpreted.


----------



## jrista (Nov 14, 2014)

I checked Sensorgen.info on the D750. According to those numbers, the maximum DR is 13.9...so slightly over capacity for the T4110, but close enough that I think it's workable. 


I also calculated the gain for ISO 100. Assuming 2^14 - 600 is the maximum numeric value, that means the gain is 81608/15784 e-/DN, or 5.17e-/DN. The read noise at ISO 100 is 5.5e-, so 5.5/5.17 = 1.064 DN. In terms of minimum read noise in a D750 NEF, the STDev can, theoretically, get as low as 1.064. I don't know what temperature DXO tests at, however temperature does play a role, as dark current noise doubles every ~5.8°C, and with read noise levels this low, even with CDS, a change in temperature can change that 1.064 to 1.1 or 1.2 or more pretty easily. 


Without accounting for temperature and dark current, the dynamic range that we are likely to measure in tests with a Stouffer wedge could very, very easily drop below the 13.9 stops as measured by DXO. So I still think that the 13.7 stops available in the wedge is good enough to measure the DR of the D750.


----------



## MichaelTheMaven (Nov 14, 2014)

Right, but it isn't 13.7, it is 13.3 (if we are overexposing the first step) and we actually agree that more real estate is needed. 

I would love to test the A7s on S-log, well past the 13 Ev mark.


----------



## jrista (Nov 14, 2014)

MichaelTheMaven said:


> Then we are going to have to respectfully disagree. If the precision your require is as outline, you cannot measure anything over 13.3 DR with a just a 13.3Ev strip. I would be happy to buy you an ND strip if you believe you can work it out.




Is the wedge 13.3 or 13.7 stops? You've stated both...just want to be sure I am on the same page as you...


If the wedge only has 13.3 stops, then yes, that is insufficient to measure the DR of the D750, even accounting for a potential loss in DR due to temperature. 




MichaelTheMaven said:


> I can see you are putting a lot of analysis into this and I really appreciate it. We agree on many points about the utilization of the wedge, but I actually think there are several ways to use it (not just one) and possibly even better tests that will come from it. Right now I am leaning towards putting a 4 stop ND filter infront of it, which technically then could get us a strip in the 17 Stop range.




Hmm, I'm confused. If you put a 4-stop ND in front of the wedge...that will darken all the swatches, no? All that does is shift the luminance output down, meaning your exposures would have to be even longer to properly saturate the exposure. But, that doesn't change the fact that each wedge is 1/3rd of a stop different. ND or no ND, the wedge represents the dynamic range it represents. 


Unless you are talking about putting an ND filter in front of only part of the wedge...say steps 41 through 21 or something like that. Then, I agree...that would increase the dynamic range, at the cost of having a large sudden drop in exposure half way through the wedge. I guess that could work...




MichaelTheMaven said:


> Additionally, what you are suggesting to overexpose the first step and only that first step on all cameras, as well as all channels is going to be just about impossible, and would make the test less quick and easy and more of a headache.
> 
> 
> My mind still isn't reconciled that what I am doing is incorrect for comparison between two cameras shooting on the same settings, so we might disagree there too and that is ok.




I agree, it would make testing more tedious. 


I do strongly assert, however, that doing so is the only way to generate a viable *comparison*. It's the only way to guarantee that all cameras expose optimally. As PixInsights statistics clearly demonstrate, the 5D III image is slightly underexposed relative to the D750 image. That is putting it at a disadvantage. I do not believe that increasing the exposure by a third of a stop (which is probably too much anyway to achieve parity with your existing D750 image) is really going to change things that much...instead of wedge 35 being the last useful wedge, wedge 36 would be the last useful wedge. Not a huge change, and in the grand scheme of things, even with your current images, pretty much all of the wedges in the range from 30-41 are riddled with color noise and banding, and are unlikely to be useful anyway without heavy NR, and after heavy NR, your going to suffer a significant loss in detail, so...how useful are they then? (And that, in a nutshell, is the cost of Canon's read noise.)


You could shortcut the process a bit. I think you underexposed by 2/3rds to 1 full stop. I would just redo the test, and increase the exposure by 2/3rds of a stop, then 1 stop, and see if either of those result in the correct output. I'm betting one of them does, so it shouldn't be all that tedious to get some better exposures on the wedges (i.e. you shouldn't have to painstakingly test each and every third stop difference to find the right one...I think the math can tell you exactly how to correct.)


----------



## jrista (Nov 14, 2014)

MichaelTheMaven said:


> Right, but it isn't 13.7, it is 13.3 (if we are overexposing the first step) and we actually agree that more real estate is needed.
> 
> I would love to test the A7s on S-log, well past the 13 Ev mark.




Well, the first step should only be clipped. To put it another way, the first step should be fully saturated. I don't believe that means your losing the first step. It just means your exposing it properly for the test case. In which case, you still have the full 13.7 stops the wedge offers. 


Anyway, it's up to you whether you want to retake the images or not. I think it would be useful, as right now, because of the exposure discrepancy between the 5D III, D750, and 7D II, we can't really compare the data and assume the results are accurate.


----------



## risc32 (Nov 14, 2014)

when this was first posted i was a bit confused because that step wedge didn't look at all like what i am used to seeing. Honestly i wanted to grab a remote and work with the white/black levels. I believe Jrista is pointing you in the correct direction. I'm ISF cert and with i used to calibrate monitors the step wedge was an important pattern, esp with digital gear. Its amazing what happens to a step pattern when you start cranking on the white/black levels with digital equipment. Not so much with analog gear, but i suppose i may as well forget anything i might know about CRT projectors... ah well.


----------



## MichaelTheMaven (Nov 14, 2014)

Ill definitely re-do it in the future, I just won't be able to do it right away. It has been a helpful discussion and scrutiny is what makes these tests better. You guys are really the only ones who are trying to help me with this, so I do appreciate it and I am listening. 

I should have expressed it more along the lines of "how can you accurately measure up to 14-15 stops of DR with a 13.7 Dr test strip", and while I have repeatedly agreed with everyone that it would be idea to overexpose that first step, with a larger DR strip, they do not exist. We can't seem to get past that point. 

In any event, I think I we might be on the same page with the ND filter over part of the existing strip. That way we can get the first part dialed in, and still have enough headroom on the dark end to measure into the 14-15Ev range.


----------



## jrista (Nov 14, 2014)

I agree, a strip with more dynamic range would be ideal. Don't those cost a lot of money, thought? I looked into the Stouffer step wedges a while back...most of them seemed prohibitively expensive...


----------



## Omni Images (Nov 14, 2014)

wooow wooow... jrista.
I read this thread today, very interesting, thank you people ...
BUT.... a strip with more dynamic range ... is this possible ?
Please explain .....
Does't the strip .. exhibit "A" already go from white 255 to black 0
How can you get a whiter white or blacker black ?
I have a lot to do with artwork and pay a lot for pantone colour books .. apparently they are printed on the worlds most expensive printer .. a 27 colour printer ... just a side note there.
Anyway I was interested to hear how you can get more DR .... does it have more increments from white to black ?


----------



## jrista (Nov 14, 2014)

It's not a matter of white, it's a matter of bright. Dynamic range has to do with signal power over noise floor. It is possible to have a wedge that transmits less in the darkest swatch and transmits more in the brightest swatch. That would then increase the ratio of brightest over darkest. So yes, it is possible. However, I don't think it is easy, hence the reason the wedges that have more dynamic range are more expensive.


----------



## Marsu42 (Nov 14, 2014)

MichaelTheMaven said:


> Ill definitely re-do it in the future, I just won't be able to do it right away. It has been a helpful discussion and scrutiny is what makes these tests better. You guys are really the only ones who are trying to help me with this, so I do appreciate it and I am listening.



+1 for your efforts, this is very interesting and beyond standard quick reviews around the net. From doing some test shots and calibration for Magic Lantern I know you only realize how complicated getting valid results really is after the first (few) attempt(s) :-\

Btw Nikon ergonomy still suc*s


----------



## garret (Nov 15, 2014)

Here a image taken from the raw data, at the right the canon 5 dmk3 and left the Nikon 750, stretch with ImagesPlus astronomical software, zero noise reduction. crop and arrows with photoshop.
Red arrows: these are white specks on the card! not noise!
Blue arrow: banding in the Canon image.
Overall: in the Nikon image you see a red hue, but way less noise.
So what you think? especial the red hue, is the card realy red or black?
Garret van der Veen


----------



## Marsu42 (Nov 15, 2014)

garret said:


> So what you think? especial the red hue, is the card realy red or black?



Did the Nikon raw processing have correct white balance? If not, there is always the option of shooting a color+wb card to calibrate - but you cannot wiz away banding that easily. 

Note: Let's not forget we're we're comparing sensors that are 2.5 years apart, for the banding the newer 6d would have been a much better choice.


----------



## privatebydesign (Nov 15, 2014)

Marsu42 said:


> garret said:
> 
> 
> > So what you think? especial the red hue, is the card realy red or black?
> ...



Marsu, that is what happens in the blacks when you lift the shadows like that on Nikon files. Having said that it is easy to remove, just do a curves adjustment layer and set the black point, this will give you the option to make different curves on the R, G and B channels to allow for the shadow hues, if you were working an important file you could use a luminosity mask on the curves to only alter specific dark tones very accurately. 

Of course if you are going to those lengths then finagling the Canon file noise/detail equation is just as easy.


----------



## Marsu42 (Nov 15, 2014)

privatebydesign said:


> Marsu, that is what happens in the blacks when you lift the shadows like that on Nikon files.



Interesting, I never shot Nikon. Why does the red tint creep in when raising shadows? And why don't they get rid of this effect - is it a basic difference between cr2 and nef files, or the sensors, or... ?


----------



## privatebydesign (Nov 15, 2014)

Marsu42 said:


> privatebydesign said:
> 
> 
> > Marsu, that is what happens in the blacks when you lift the shadows like that on Nikon files.
> ...



I don't know, but the colour fidelity and tonality degradation is dramatic. Whilst there is no doubt that the Exmor files can be lifted much more than Canon files it certainly isn't a free lunch and the actual quality of the information down in those dark shadows is limited. I have said many times, and I have printed a lot of Nikon files, when the lifted areas take up more than a small area of the image the file ends up looking very flat, the tonality just isn't there and that is because of the gamma curves that are already applied to the RAW information, to then apply another gamma shaped curve on top of that stretches the few tones to nothing.


----------



## jrista (Nov 15, 2014)

Marsu42 said:


> privatebydesign said:
> 
> 
> > Marsu, that is what happens in the blacks when you lift the shadows like that on Nikon files.
> ...




It just looks like a difference in white balance to me. The red shift in the Nikon file appears throughout the level scale...it affects the brighter tones as much as it affects the darker tones.


----------



## jrista (Nov 15, 2014)

garret said:


> Here a image taken from the raw data, at the right the canon 5 dmk3 and left the Nikon 750, stretch with ImagesPlus astronomical software, zero noise reduction. crop and arrows with photoshop.
> Red arrows: these are white specks on the card! not noise!
> Blue arrow: banding in the Canon image.
> Overall: in the Nikon image you see a red hue, but way less noise.
> ...




I am pretty sure the red hue is just due to white balance. I do not believe that is the correct color, but it is easily correctable. The card and wedge should be neutral in color.


----------



## privatebydesign (Nov 15, 2014)

jrista said:


> garret said:
> 
> 
> > Here a image taken from the raw data, at the right the canon 5 dmk3 and left the Nikon 750, stretch with ImagesPlus astronomical software, zero noise reduction. crop and arrows with photoshop.
> ...



It is not as simple as the white balance, if it was all the whites would also be as red, and they are not, don't confuse the magenta fringing as red toned whites. If you look at a channel histogram you can see the red shift in the shadows and a slight lack of red in the highlights. 

It is due to changes in the response curve at different tones which could be caused by any number of fundamental things, the only way to sort it out is to apply a channel tone curve, probably several with luminosity masks, to overcome the precise shifts.

The first histogram is the untouched file, the second is the three point three channel corrected file, I have included the tone curve adjustment lines too. Although the resulting lines look linear they are not. And, of course, any adjustments you make to the actual shadows would need a similarly adjusted curves layer.

None of this is that difficult, but the time and skill involved is not as trivial as many would lead you to believe good processing of Exmor files is.


----------



## jrista (Nov 16, 2014)

privatebydesign said:


> jrista said:
> 
> 
> > garret said:
> ...




I have not yet opened up the files in a RAW editor. I am still looking at them in PixInsight. As far as I can tell, the white swatches in the NEF are just as redshifted as the black swatches. The overall red hue appears to be consistent to me, at least when the image is rendered in linear space. I can do a non-linear screen stretch, and the red hue disappears and the entire image becomes neutrally balanced.


You can look at the JPEG images I shared in my post a couple of pages back. The Canon image appears to be very slightly blue shifted in the white swatches, while the Nikon image appears to be red shifted in the white swatches. I can share more images...I don't think there is any discrepancy in the red shift between the swatch 1 and swatch 41, or the background for that matter.


----------



## privatebydesign (Nov 16, 2014)

jrista said:


> As far as I can tell, the white swatches in the NEF are just as redshifted as the black swatches. The overall red hue appears to be consistent to me, at least when the image is rendered in linear space. I can do a non-linear screen stretch, and the red hue disappears and the entire image becomes neutrally balanced.



If it was a simple colour shift or WB issue then the three lines in the channel curves adjustment would be straight, but they are not, they are curves. Being curves means the respective colour balance is uneven at different tonalities.


----------



## jrista (Nov 16, 2014)

privatebydesign said:


> jrista said:
> 
> 
> > As far as I can tell, the white swatches in the NEF are just as redshifted as the black swatches. The overall red hue appears to be consistent to me, at least when the image is rendered in linear space. I can do a non-linear screen stretch, and the red hue disappears and the entire image becomes neutrally balanced.
> ...




A assume you are working with images that have passed through one RAW converter or another? I am looking at the RAW linear data...and I am not seeing what you are seeing. Is it possible the RAW converter is complicating things?


----------



## privatebydesign (Nov 16, 2014)

"Is it possible the RAW converter is complicating things?"

Of course it is, but it could as easily be an intrinsic capture issue, but the point is moot, this isn't an isolated set of images and more than one RAW convertor does the same thing. Besides the output is purely academic until you put it through a RAW convertor, and the number of images most of us shoot means it needs to be one of a small handful of those.

Like I said, it isn't a huge issue for people with above average expectations and post processing skills.


----------

