# First impressions - A7R III preproduction unit



## Talys (Nov 3, 2017)

My local camera shop had a preproduction A7R III and a 24-105 in for folks to see, and I was fortunate enough to have had the opportunity to play with it for about half an hour. Here are my observations and first thoughts, keeping in mind that it was a preproduction unit with early firmware. They did not permit me to put a memory card in the camera to keep any shots 

1. Viewfinder - The viewfinder was easily an order of magnitude better than A7R II. Mostly gone is the jello effect, and it is actually quite pleasant to use for subjects that are still, or for subjects that are slow-moving (like walking). It's very sharp and very clear. 

The viewfinder still blurs when you pan the camera. For example, I pointed it at a large sign that said SONY, and zoomed in such that the letters filled about 3/4 of the viewfinder horizontally. When I panned even slowly, the letters suffered from visible motion blur. Not as badly as A7R II, not even remotely close to the experience of an optical viewfinder.

In addition, for some reason, the viewfinder started to stutter in jarring (unusable) way when the camera was in continuous autofocus. When I pointed it out to the Sony guy, he reset the camera, and that went away. He blamed it on preproduction firmware, which is entirely plausible. He also said that they had a number of other issues with that unit. 

2. Autofocus - On the 24-105, autofocus was smooth, quick, and apparently accurate when using people as subjects. I say apparently, since there's no way to tell with no memory card. But, it didn't stumble, and the experience was favorable. The default intelligent mode, where the camera seems to figure out what you might want to focus on is kind of crazy, because it seemed to just randomly grab a person walking by, when I was clearly pointing at a tripod. And if there's multiple people in the scene, I have no idea how it figures out who to focus on. Where there was only 1 human, it always reliably identified the person and set AF to the face (AF face detection was on).

The Joystick is a very, very welcome. It worked well when the camera was set to center point. When nonhuman subjects were far away (15 ft+), AF seemed to be quick and responsive with centerpoint. However, when objects were close (3-6ft), center point sometimes did not focus on what I wanted it to. It was quite reproducible, and the explanation was that this was a preproduction unit.

I was also permitted to attach a G-Master 70-200/2.8. On the plus side, the lens on the camera feels very balanced, and the rig feels nice. But the good news ended there. The autofocus was horrible - it hunted a LOT, at times unusably so for a subject like a price tag at about 6 feet. It would actually go back and forth and stutter like it was having a seizure, never locking on. Again, this was blamed on preproduction.

It did seem to AF better at f/2.8 than stopped down to f/5.6. Could it be that there wasn't enough light? Either way, it would not be acceptable to me in a production unit.

3. FPS, Buffer, Uncompressed vs Compressed RAW - The Sony guy tried to sell me on Compressed RAW, which lowers it to 12 bit (from 14), and also drops the file sizes from 100MB / file to about half that. He claims that the differences are not detectable, but of course, there's no way to without recording photos. He told me 26 frame buffer in uncompressed mode, and seventy-something (76?) in compressed, either of which is very impressive, especially considering the FPS. 100MB / file... aie carumba. 600 photos, and a 64GB card would be full LOL.

He mentioned that he filled a 128GB card pretty quick. So, it's worth thinking about before buying a 40+ megapixel camera, the cost of larger memory cards, since 128 will be the new 64, and if you want them UHS2, that adds to the total cost of ownership.

4. Buttons, Build, and Egonomics - There are a lot more buttons, which is very welcome, and a rear dial, of course. However, on the down side, there are still way too few buttons. There are many, many things that Canon cameras have dedicated buttons for, like changing AE, Focus, ISO, Drive, etc. -- and on the Sony, the answer is "program it to one of the custom buttons". But the problem is, there aren't nearly enough, at least for me. The dials also had a certain, non-industrial cheapness to them, in comparison to Canon or Nikon dials, but maybe that's just me.

In terms of ergonomics, it's feels just like the A7RII. So if you like that, you'll like this, and if you didn't you'll still hate it. There are a million threads about Sony A7RII ergonomics, so I'll just skip right past it, except to say that personally, they have always felt ok with smaller lenses, and awkward with anything larger than a 70-200.

I guess it's to be expected since the build hasn't changed, but the A7R III still feels like a delicate flower. I think I would hesitate to use it in a situation where I might drop it, because it doesn't _feel_ like it would survive that kind of handling. Or, bashing it against something accidentally. Though uncommon, it's not like I've never done those things to my cameras.

5. Techno-gizmo-features - This camera is PACKED with them. There are so many features that I didn't even know where to start to explore them, and I certainly wouldn't do any justice trying to pass on my observations, because I really didn't know what I was doing. How many of those features would actually be useful, I have no idea.

Oh, it had 2 card slots, Yay. On the minus side, the remote trigger uses a mini USB -- it shares this with the computer connection. I say that's a minus, because this is much , much more fragile than mini mic/N3, and it certainly is not water resistant like N3. On the other hand, it doesn't seem like the A7R II survives water very well, so maybe this is more a fairweather camera. Plus, you can't tether AND use a remote trigger, right?

6. Other things mentioned - The battery seems much improved, and they brought up 5.5 stops of IS, over 4 stops, which is pretty amazing. He also brought up more dynamic range, claiming 15 stops. Really? I thought the sensor output was not much different than A7R II. Whatever. I just thought it was cute that this was on the list of things to rattle off to potential customers. Along the same lines, he also brought up some HDR stuff, which is also unexciting to me.

Ironically, everyone there universally suggested that I buy the Sigma MC11 adapter to use with the Sony body so that I could preserve my Canon lenses. The camera shop guy pointed out that comparable Canon lenses were MUCH cheaper, and the Sony guy chimed in that with the Sigma adapter, all of the advanced Sony features would work, and that he preferred this over the metabones adapter that was twice the price (wait, so he uses Canon lenses with his Sony?).

The Sony guy mentioned that on the video end, there were advantages to using the native Sony lenses, but since I identified right at the beginning that that I didn't give a flying fart about video, he said that for photographs, Canon lenses would work every bit as well (as Sonys). Which was just kind of stunning to hear from him, I guess. 

The Camera store person chimed in that this would also allow me to use the lenses with my Canons. Really? I would have never thought of that!

OTOH, I suppose Sony guy might have been a Sony champion of some sort, rather than a Sony employee. He was wearing a Sony shirt, though 8)

Final thoughts -- well, at this moment, even if I really wanted one, after seeing the preproduction unit, I sure wouldn't buy one, until it came out and I was sure the bugs were all ironed out. Boy, were there a lot, for a unit that they were demonstrating to the general public. Maybe I'm being unfair, but it feels like it's rushed to make Christmas.

That said, would I buy one, if it were bug free? There are a lot of things to really like about it, but I think the EVF still has to get a little better before it would be useful -- or at least, not migraine inducing -- for my style of birding. I would need to see AF on the final version, and it would have to be a lot better on lenses that I'd use before I'd consider it, too. At the price, I don't think that these things should have to be compromised on.

The remote shutter might kill it for me too, because I use a wired remote trigger a lot (no batteries), and micro USB is not a good connector for that, in my opinion. Plus, I do not like the idea of not being able to tether and have a wired trigger at the same time.

Would I buy one if it were a Canon, in a Canon body, with Canon ergonomics? _Maybe_. Which is saying a lot, because (a) it's more than I would think of spending on a body and (b) because the EVF still isn't as pleasant to use as an OVF, and having fun shooting is very important to me in photography as a hobby. Still, it gives hope for me as a mirrorless customer, I guess!

Still, it was lots of fun to check out and well worth the half hour.


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## Ryananthony (Nov 3, 2017)

Thank you  I missed Broadway Cameras Demo days.


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## Talys (Nov 3, 2017)

Ryananthony said:


> Thank you  I missed Broadway Cameras Demo days.



Yup! That's where the event was at. There were 5-6 employees + Sony fellow (I forget his name, even though I asked  ). Literally nobody else came in for anything, during the 30-45 minutes that I was there.


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## Jopa (Nov 3, 2017)

Talys, thank you for the review! Finally a *non-biased non-paid* one. 

#2 you can define in the camera - either disable the face detection completely (if you don't want the camera to prioritize on faces) or if you care about a particular person - register their face so the camera would pick that person out of the crowd. It does require you to digging into the menu though 

As far as I remember they demoed the A7r2 to bloggers with the 24-105 only, so most likely the firmware was fully ready only for this lens and the Sony guy wasn't aware of this fact (otherwise he won't let you to mount the 70-200  ). Most likely your assumption the camera was rushed towards Christmas is correct.


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## ahsanford (Nov 3, 2017)

Talys, well done. Really appreciate the detail.

Thoughts (my numbers don't correspond to yours):

1) -1 on 128 GB+ cards. I prefer to keep them smaller as my PC chokes in general trying to scan/triage what's on the card, what's new vs. what's already been imported, even basic searching for a specific shot number for RAW ACR work, etc. I've noticed considerably better performance / less head-banging and spinning wheels with 64 GB cards. I don't know if this is a card reader I/O speed issue or just the pains of having the PC quickly sift through so much data.

2) Surprised to hear you say it feels like an A7R II when it has the added thickness of the A9 and that new joystick.

3) Regarding 15 stops DR: Sony claims it's the same sensor but it has some new pipeline/architecture handling it. We'll see how that pans out.

4) 'Sony advantages with their lenses for video' _may_ stem from all of their glass being FBW, but I'm no video jockey. In comparison, a (say) L lens with mechanical override ring USM (i.e. ideal for _stills_) may demonstrate video AF in a jumpy fashion compared to something more like a Sony stepping motor FBW lens.

5) I'm personally surprised a camera company eager to get professionals is walking around a pre-production model with such glaring issues -- it might only reinforce concerns that mirrorless isn't worthy of their business yet. It's one thing if you need to reset it, menus lack polish, etc. but AF needs to work, $2500 lenses needed to sing with it, etc.

Again: nice work! 

- A


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## SecureGSM (Nov 3, 2017)

That 15 stops if DR claim was a one tough call. Sony Marketing guys smoke too much wacky stuff as of late.

http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205D%20Mark%20IV,Sony%20ILCE-7RM2,Sony%20ILCE-7RM3




ahsanford said:


> 3) Regarding 15 stops DR: Sony claims it's the same sensor but it has some new pipeline/architecture handling it. We'll see how that pans out.
> 
> 
> - A


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## Jopa (Nov 3, 2017)

SecureGSM said:


> That 15 stops if DR claim was a one tough call. Sony Marketing guys smoke too much wacky stuff as of late.
> 
> http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205D%20Mark%20IV,Sony%20ILCE-7RM2,Sony%20ILCE-7RM3
> 
> ...



I bet that's _DxO stops_ not the real ones. And I'm pretty sure DxO can "fine tune" the DR so it will look like 15. Sony is a partner and a sensor supplier for their crappy camera.


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## Talys (Nov 4, 2017)

@SecureGSM - We have good weed in BC. It's like 4k HDR weed! 

@Jopa - I think it didn't matter to him what kind of stops they were, as long as it was more a bigger number than the Nikon D850 

Sony guy put a lot of emphasis on how the A7RIII was "Better than Nikon", comparing some direct stats and also some stuff like Nikon cheats on many of its claims because they are only technically true under specific, conditions (something that Sony would never do, of course). 

Perhaps noteworthy, he barely mentioned Canon except to say that he used to shoot Canon but got tired of new cameras without great features. If anything, the subtext was Sony A7RIII + Canon Lens = win, so please preorder an A7RIII!

In other threads people have mentioned that perhaps the true motivators for launching cameras with various feature sets is between Sony/Nikon for the #2 spot, rather than either making a run at the #1 spot. 




Jopa said:


> SecureGSM said:
> 
> 
> > That 15 stops if DR claim was a one tough call. Sony Marketing guys smoke too much wacky stuff as of late.
> ...


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## Mt Spokane Photography (Nov 4, 2017)

Thanks for the detailed writeup. I did not get to read it all, but enjoyed what I did read.


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## bwud (Nov 4, 2017)

Jopa said:


> I bet that's _DxO stops_ not the real ones.



I really doubt they're downsampling before publishing a camera specification. The trade group they belong to (CIPA) requires ISO 15739 be used to measure and publish dynamic range specification, and ISO 15739 doesn't involve downsampling.

There has been some talk of the camera working in 16-bit until writing to the 14-bit RAW container. ISO 15739 specifies for cameras with removable lenses that a light source (with specific reqts) be set such that the camera it just shy of clipping. Maybe the sony in capture mode with 16-bits has a modicum more headroom than the 14-bit container (i.e. the pixel saturation exceeds a 14-bit container), and that works to their advantage when evaluating the noise.

Either way, I would be very surprised if they would completely depart from the industry standards to which they're a member.


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## SecureGSM (Nov 4, 2017)

here:

http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205D%20Mark%20IV,Sony%20ILCE-7RM2,Sony%20ILCE-7RM3

measured against A7RII and 5D IV. yes, in camera exposure blending ( Multi Pixel shift whatever mode) - will "extend" DR somewhat wide, of course. that is, likely, where this 15 stop of DR claim is originated from 



bwud said:


> Either way, I would be very surprised if they would completely depart from the industry standards to which they're a member.


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## bwud (Nov 4, 2017)

SecureGSM said:


> here:
> 
> http://www.photonstophotos.net/Charts/PDR.htm#Canon%20EOS%205D%20Mark%20IV,Sony%20ILCE-7RM2,Sony%20ILCE-7RM3
> 
> ...



I was referring to sony’s claim of 15 stops, not Bill Claff’s measurements.


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## privatebydesign (Nov 4, 2017)

bwud said:


> SecureGSM said:
> 
> 
> > here:
> ...



The problem in all this is not what it is measured, it is where you put the goal posts.

The 'industry standard' is a laughably unusable irrelevance that consigns much of that DR into noise levels that mean there is no usable image data, Bill Claff has chosen a SNR of 20%, which is a point at which he believes shadow detail is lost to noise (and I am not saying he is incorrect).

The root of the issue is we all have different ideas on what is usable, or correctable, noise levels in our images. Sometimes a SNR of 20 is perfectly OK, other times maybe not, but we have to set a baseline somewhere and to his credit he goes to lengths to explain and rationalize his methodology.

Interestingly, and I'd like to hear his reasoning, some here have argued that 14 stops in 14 bit files isn't necessarily a hard limit as a log curve could be applied to the linear sensor data in camera, his assumption is that 14 stops of DR is a limit in 14 bit files and his calculations are based on 14 stops minus the amount lost to the 20% SNR. That is beyond my expertise so an informed input on that specific would be welcome.


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## ahsanford (Nov 4, 2017)

bwud said:


> I was referring to sony’s claim of 15 stops, not Bill Claff’s measurements.



Surely they meant in DXO's terms, in which a few EXMOR sensors have been sitting around 14.5 in the past few years.

- A


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## Jopa (Nov 4, 2017)

Talys said:


> Sony guy put a lot of emphasis on how the A7RIII was "Better than Nikon", comparing some direct stats and also some stuff like Nikon cheats on many of its claims because they are only technically true under specific, conditions (something that Sony would never do, of course).
> 
> Perhaps noteworthy, he barely mentioned Canon except to say that he used to shoot Canon but got tired of new cameras without great features. If anything, the subtext was Sony A7RIII + Canon Lens = win, so please preorder an A7RIII!



That sounds plain ugly. Sony is trying to convince everybody to "switch", promising their photography will significantly improve, and everybody who switched will get a Pulitzer no doubt. _It's ok that we're still developing the system and it's buggy as h3ll, but it's cool, you switch and we'll figure out everything later._
Sony A7RIII + Canon Lens = lousy AF, but yes, please pre-order an A7RIII.


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## bwud (Nov 4, 2017)

ahsanford said:


> bwud said:
> 
> 
> > I was referring to sony’s claim of 15 stops, not Bill Claff’s measurements.
> ...



If they did mean it that way, someone in marketing should be fired. Maybe the asterisk “Sony test conditions” is their attempt at absolving themselves of the CIPA requirement that Dynamic Range be determined and specified per ISO 15739, but it’s particularly weak. Maybe next they’ll start reporting ISO speeds with the electronics liquid cooled.

ISO requires that if test conditions aren’t to standard that they be listed along side the results, and further requires that lossy compression, which would include downsampling, be disabled if possible (which it is).

Full disclosure my copy of ISO 15739 is revision 2003. Maybe they’ve since added a provision for downsampling. However I can think of no instance in which electronics or electrical components of which DR is a significant parameter are permitted by standard to specify a downsamped value.

An enthusiast website like DXOmark which concerns itself with making comparisons on a normalized basis is a whole
different ballgame than a device manufacturer reporting a single spec.

I’m not convinced either way.


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## bwud (Nov 4, 2017)

privatebydesign said:


> bwud said:
> 
> 
> > SecureGSM said:
> ...



The goal posts should be put where the international standard specifies: SNR=1 under standard lighting and target with 18% reflectance reference, etc. 

Forget what the various websites do, I’m talking an advertised camera specification. The trade group of which Sony is a member has a meaningful standard. If they’re violating that standard they should be taken to task for it.

At the risk of posting intellectual property:


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## privatebydesign (Nov 4, 2017)

bwud said:


> privatebydesign said:
> 
> 
> > bwud said:
> ...



Why? It's a meaningless number that tells you nothing about how much DR you can actually photograph in real life. Taking figures like 20% SNR get you closer to what you will actually be able to take pictures of, hence it's name, *Photographic* Dynamic Range, and Mr Claff gives in detail descriptions between the differences in Photographic Dynamic Range and the oft quoted and utterly irrelevant Engineering Dynamic Range.


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## scottkinfw (Nov 4, 2017)

Talys said:


> @SecureGSM - We have good weed in BC. It's like 4k HDR weed!
> 
> @Jopa - I think it didn't matter to him what kind of stops they were, as long as it was more a bigger number than the Nikon D850
> 
> ...


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## bwud (Nov 4, 2017)

privatebydesign said:


> Why? It's a meaningless number that tells you nothing about how much DR you can actually photograph in real life. Taking figures like 20% SNR get you closer to what you will actually be able to take pictures of, hence it's name, *Photographic* Dynamic Range, and Mr Claff gives in detail descriptions between the differences in Photographic Dynamic Range and the oft quoted and utterly irrelevant Engineering Dynamic Range.



There is a reasonable argument to change the standard. Standards are revised frequently (the noise measurements standard which includes DR requirements was as recently as this year).

However if they sign up to it (and I take their membership in the trade group as evidence they do) they should follow it. “Say what you’ll do, do what you said.”

Regardless, my argument here isn’t in favor of the standard’s content, it’s with the notion they downsampled the data before computing, or computed and ratioed to approximate a downsampled value a’la DXOmark. If they did that, bad on them.


I think there is an over abundance of hype regarding DR. Most every modern camera capable of raw recording with a sizeable sensor has excellent range. But if they’re going to specify it, they should do so to the peer reviewed standard.


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## bclaff (Nov 5, 2017)

privatebydesign said:


> ...
> ... Bill Claff has chosen a SNR of 20%, ... Sometimes a SNR of 20 ... his assumption is that 14 stops of DR is a limit in 14 bit files and his calculations are based on 14 stops minus the amount lost to the 20% SNR....


It's an SNR of 20; not an SNR of 20%.
There is no assumption that 14-bit ADC limits dynamic range to 14.


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## bclaff (Nov 5, 2017)

bwud said:


> ...


FWIW.
The Sony claim cites neither CIPA nor DxOMark; it has no concrete foundation.
It simply says "Sony test conditions for stills"; whatever that means.


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## Jopa (Nov 5, 2017)

bclaff said:


> bwud said:
> 
> 
> > ...
> ...



That's funny. Next time they'll simply say "because we say so" ;D


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## privatebydesign (Nov 5, 2017)

bclaff said:


> There is no assumption that 14-bit ADC limits dynamic range to 14.



Then I don't understand why your explanation page runs to 14 and your figures are 14 minus the amount lost to < SNR 20.
_"Here is a chart of the Photon Transfer Curve for the Nikon D300 in ADUs at all whole ISOs based on 14-bit ADUs: "_

http://www.photonstophotos.net/GeneralTopics/Sensors_&_Raw/Sensor_Analysis_Primer/Engineering_and_Photographic_Dynamic_Range.htm

I understand 14 bit ADU's can represent any range of values with 16,384 steps, and that an ADC doesn't count 1:1 photons to these steps, what I don't understand is where the 14 stops of DR as a base comes from.

So, for example, a full well capacity for a pixel is 100,000 photons. The 14 bit ADC can change that 0-100,000 photons of electric charge into any one of 16,384 values, or ADU's, giving a 14 bit ADU. I understand that if it took 20 stops of DR to capture a full range of photons across the sensor then the 16,000 steps would represent 20 stops of DR, but that doesn't seem to be how it works and again I don't understand where your 14 stop start point comes from.

Would be grateful of an explanation from somebody who actually understands!


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## bwud (Nov 5, 2017)

bclaff said:


> bwud said:
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> 
> > ...
> ...



I know, I’m basing my premise on their CIPA membership.


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## bclaff (Nov 5, 2017)

privatebydesign said:


> bclaff said:
> 
> 
> > There is no assumption that 14-bit ADC limits dynamic range to 14.
> ...


This comes up enough that a separate article on PhotonsToPhotos is called for.

First note that the chart you make reference to has a logarithmic x-axis.
It's true it ends on the right at 14 but it also runs to minus infinity on the left even though that particular one ends at 0.

Remember, read noise is a standard deviation; so although each ADC reading is integral the standard deviation is not, and can be less than 1.
Because of quantization error in practice we can't measure below about 0.6 DN
( see http://www.photonstophotos.net/GeneralTopics/Sensors_&_Raw/Quantization_Error_in_Practice.htm )
0.6 is nearly 0.75 stops better than you might expect but to be conservative I typically say that an n-bit ADC can measure n+0.5 stops of dynamic range; 14.5 stops for a 14-bit.

I rarely test a sensor with 14-bit ADC with more than 14 stops of EDR; the Nikon D7200 is an example.
This happens more often with 12-bit ADCs; I assume these cameras don't use 14-bit due to cost considerations.
A 12-bit example is the Panasonic GX80.
Even the 10-bit ADC in the Samsung S6 phone isn't enough at ISO 50.
Attaching (note logarithmic y-axis, below 0 is below 1DN ):
http://www.photonstophotos.net/Charts/RN_ADU.htm#Nikon%20D7200_14,Panasonic%20Lumix%20DMC-GX80_12,Samsung%20Galaxy%20S6(S5K2P2)_10


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## Mikehit (Nov 5, 2017)

bclaff said:


> [
> This comes up enough that a separate article on PhotonsToPhotos is called for.
> 
> First note that the chart you make reference to has a logarithmic x-axis.
> ...



I don't know enough about the technical stuff going on here, but on first reading it is starting to sound like there is so much electronic jiggery-pokery along with each company's interpretation of the definitions that it is becoming hard to believe what any company is saying any more because there is no hard and fast definition of what constitutes acceptable noise, or dynamic range. 
The MP wars have got to the point that 30MP vs 45 MP? Who really cares. And dynamic range seems pretty much the same. Everyone is fighting over scraps at the table


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## privatebydesign (Nov 5, 2017)

Mikehit said:


> ..... there is no hard and fast definition of what constitutes acceptable noise, or dynamic range.
> The MP wars have got to the point that 30MP vs 45 MP? Who really cares. And dynamic range seems pretty much the same. Everyone is fighting over scraps at the table



Yep, and I keep pointing that out, not that the forum DRones or measurbators care........

http://www.canonrumors.com/forum/index.php?topic=33696.msg694260#msg694260

http://www.canonrumors.com/forum/index.php?topic=33709.msg693866#msg693866


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## bwud (Nov 5, 2017)

Mikehit said:


> ... because there is no hard and fast definition of what constitutes acceptable noise, or dynamic range.



Oh yes there is. The trade group the major camera makers (including Canon, Fuji, Nikon, Sony, and Ricoh) belong to has a (non-mandatory) guideline as to how camera specifications should be evaluated and expressed in order to "...inform consumers of product specifications fairly and accurately and to develop a sound market and digital camera business by encouraging fair competition..." That guideline includes dynamic range, in specific:


> Shall comply with ISO 15739:2003 (an outline is shown below).
> *1. Definition*
> This means the ratio of the maximum level of luminance signals without saturation to the level of luminance signals where the S/N ratio to random noise is 1 (the minimum level of luminance signals)



Many people don't like that definition applied to camera products, and with good reason, but rather than petitioning ISO to change the standard, they come up the myriad hodgepodge of formulae we see in the marketplace (mostly in testing websites since few vendors publish DR). 

However, there most certainly and definitively exists a hard and fast definition of what constitutes dynamic range: ISO 15739:2003 Photography -- Electronic still-picture imaging -- Noise measurements. Additionally, there is commercially available software to test per ISO, such as Imatest.

I pose a question to Bill Claff: if you defined dynamic range per the ISO standard, with the data you collected, what value would you compute?


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## privatebydesign (Nov 5, 2017)

bwud said:


> Many people don't like that definition applied to camera products, and with good reason, but rather than petitioning ISO to change the standard, they come up the myriad hodgepodge of formulae we see in the marketplace (mostly in testing websites since few vendors publish DR).



When Canon did that with their Cinema cameras they were absolutely hammered over it.

As for the Claff ISO standard, surely in his work that equates to the Engineering Dynamic Range.


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## bwud (Nov 6, 2017)

privatebydesign said:


> bwud said:
> 
> 
> > Many people don't like that definition applied to camera products, and with good reason, but rather than petitioning ISO to change the standard, they come up the myriad hodgepodge of formulae we see in the marketplace (mostly in testing websites since few vendors publish DR).
> ...



You’re probably right (his EDR figure). I’m just curious if Sony has any leg to stand on, assuming its data isn’t dramatically different, WRT the claimed 15-stops (without relying on noise reducing downsampling). My guess is *no*, but then again as you note Canon published data, and though they took heat for it, they backed it up with an entirely different method (instrumentation).


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## bclaff (Nov 6, 2017)

bwud said:


> Mikehit said:
> 
> 
> > ... because there is no hard and fast definition of what constitutes acceptable noise, or dynamic range.
> ...


There no need to cite any ISO or other standard; dynamic range at the pixel level is always defined that way.
Because there are other normalized dynamic range measures I always call this Engineering Dynamic Range (EDR).
For the 7R Mark III I have complete data; attached below (and compared with the Mark II)
( http://www.photonstophotos.net/Charts/RN_ADU.htm#Sony%20ILCE-7RM3_14 )
The numbers are shown (mouse overe data points) with too much precision but the answer is unaffected.
log2((16383DN-512DN)/1.257DN) = 13.6 stops
512DN is known as BlackLevel.
1.257DN is the lowest read noise (measured at ISO 50); but even if you substitute 1.275DN at ISO 100 you still get 13.6 stops.
Note this isn't close to 15, nor is any existing camera; hence the assumption that this can't be what Sony means.
BTW, for the 7R Mark II it comes out 13.3 stops; so the Mark III is a 0.3 stop improvement in EDR.


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## bwud (Nov 6, 2017)

Thanks Bill.


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## Talys (Nov 6, 2017)

bwud said:


> Thanks Bill.



+1 ... interesting, and thanks, Bill!


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## snoke (Nov 6, 2017)

bclaff said:


> privatebydesign said:
> 
> 
> > bclaff said:
> ...



Who make Panasonic sensor? GX80 read noise under FF DSLR, yes?


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## bclaff (Nov 6, 2017)

snoke said:


> ...
> GX80 read noise under FF DSLR, yes?


Comparing per pixel read noise in DN is senseless.


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## snoke (Nov 7, 2017)

bclaff said:


> snoke said:
> 
> 
> > ...
> ...



Don't understand presentation if senseless. How to use graph?


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## tron (Nov 7, 2017)

hello,

the comments below are addressed to Sony and not yourself of course.

On the contrary I would like to thank you for providing us with your detailed feedback.



Talys said:


> ...
> In addition, for some reason, the viewfinder started to stutter in jarring (unusable) way when the camera was in continuous autofocus. When I pointed it out to the Sony guy, he reset the camera, and that went away. He blamed it on preproduction firmware, which is entirely plausible....


It is plausible but not certain. 




Talys said:


> He also said that they had a number of other issues with that unit.


 Alarming...


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## tron (Nov 7, 2017)

Talys said:


> Final thoughts -- well, at this moment, even if I really wanted one, after seeing the preproduction unit, I sure wouldn't buy one, until it came out and I was sure the bugs were all ironed out. Boy, were there a lot, for a unit that they were demonstrating to the general public. Maybe I'm being unfair, but it feels like it's rushed to make Christmas.


+ 1000


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