# Dynamic Range questions..



## TeT (Sep 26, 2014)

I have found mixed information on the following question depending upon where I look and no hard data to back any of the answers up. 

Following considers proper exposure ranges in regards to speed and aperture setting 

Does DR decrease as ISO increases and does it decrease at a steady rate. AND Will camera A with DR of 12 still have higher DR than camera B with DR of 10 when both are tested at ISO 1000 4000 or 8000.


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## ajfotofilmagem (Sep 26, 2014)

In general, Sony EXMOR has more DR until ISO400. Canon has more DR at ISO above 1600. Find specific data to make a fair comparison of camera models.


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## neuroanatomist (Sep 26, 2014)

Yes, it depends on the sensor, and it depends on the sensors being compared (respectively). 

DxOMark plots the full stop measurements (use the Measurements tab) for each sensor. Bill Claff (Google Claff D70) plots DR vs. ISO in 1/3 stop increments for select sensors.


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## TeT (Sep 26, 2014)

ajfotofilmagem said:


> In general, Sony EXMOR has more DR until ISO400. Canon has more DR at ISO above 1600. Find specific data to make a fair comparison of camera models.



I am finding data, but not always available to look at the data I want with the camera I want to see it on... Everyone tests and plots results differently...

I am finding that my 6D has fair DR at 100 and a very high DR in comparison at higher ISO's.

FYI: 800 to 2000 is probably my normal range


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## Marsu42 (Sep 26, 2014)

ajfotofilmagem said:


> In general, Sony EXMOR has more DR until ISO400. Canon has more DR at ISO above 1600.



I certainly am not interested in any dr mud slinging, but it has to be noted that Sony's advantage at low iso is very large and noticeable while Canon's advantage at higher iso (see individual model dr curves) are minor.

I'm generally looking here, though it's mostly dxo data: http://sensorgen.info/



TeT said:


> I am finding that my 6D has fair DR at 100 and a very high DR in comparison at higher ISO's.



My standard comment: Use Magic Lantern's dual_iso, it boosts your dynamic range at iso 100 to about 14.5+ stops at (nearly) no loss of iq but usability hassle. It also will have a mini_iso module in the near future adding 1/3-1/2 ev of dynamic range just like that, it's about the same optimization Canon did to the 1dx.


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## ajfotofilmagem (Sep 26, 2014)

Marsu42 said:


> ajfotofilmagem said:
> 
> 
> > In general, Sony EXMOR has more DR until ISO400. Canon has more DR at ISO above 1600.
> ...


Yes, the advantage of Canon in DR above ISO1600 is not big but I think its important that people know that EXMOR sensors are not the best in all situations.


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## TeT (Sep 26, 2014)

Well that clears the air a little for me.

In reading all of the DR posts, I was seeing a lot of numbers from comparisons of sensors at their highest DR which is usually at ISO 100 or so...

How many PPL actually do the majority of their shooting at 100? Was looking for more...

Some (but not many) of the charts and tests results on sites allude to DR falloff throughout the ISO range but its hard to find hard data on more than a few cameras.

ALSO more recent tests and results seem to be less comprehensive in data than those made 5 years ago...

anyways... thanks for your input


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## Mt Spokane Photography (Sep 26, 2014)

Marsu42 said:


> ajfotofilmagem said:
> 
> 
> > In general, Sony EXMOR has more DR until ISO400. Canon has more DR at ISO above 1600.
> ...



The thing to consider, is that very high ISO's like I often use, there is very little DR to begin with. Even a small amount is a big improvement. When DR is only 5 stops, 1/2 stop is a noticible improvement for virtually every photo, but the average photo has no noticible improvement with a 20% DR at ISO 100, you have to have poor lighting with deep shadows or a poor exposure to see the benefit.


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## jd7 (Sep 27, 2014)

Mt Spokane Photography said:


> Marsu42 said:
> 
> 
> > ajfotofilmagem said:
> ...



+1. That is the conclusion I came to as well. 

I have to admit I haven't personally tested an Exmor sensor camera to see for myself exactly how much difference Exmor makes at low ISO in real world shooting (or at least my real world shooting!), so I suppose that means take my opinion with a grain of salt, but _for my needs_ DR/latitude at higher ISOs seems more important - noting I'm pretty happy with the photos I get with my 6D at low ISO even if they may lag behind what Exmor can produce. (I really should get hold of a camera with Exmor one day and try it out for myself, I guess.)

I don't understand all the threads (I'm not talking about this one) which degenerate into heated dispute about Canon v Exmor DR. Every system has a set of trade offs so it is just a case of choosing which set of trade offs suits you personally prefer. Some photographers will value DR/latitude at low ISO very highly, in which case a system which includes a camera with Exmor is likely to be very attractive (subject to weighing up all of the other trade offs, of course). Others won't value DR/latitude at low ISO so highly, so a system which includes a camera with Exmor isn't necessarily as appealing (but again, subject to weighing up all of the trade offs). All else being equal I'm all for more DR if it is on offer, but in reality all else is not equal.


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## Marsu42 (Sep 27, 2014)

Mt Spokane Photography said:


> The thing to consider, is that very high ISO's like I often use, there is very little DR to begin with. Even a small amount is a big improvement.



True, but my consequence of this is different: You cannot shoot high-dr scenes at high iso *anyway*, so why bother - it simply needs more control or acceptance that you'll get clipped highlights in some parts.

On the other way, 2-3 ev more dr at low iso really makes a difference in practical terms for me: I can shoot outdoors noon, with very bright sky and deep shadows or with the sun in the frame. An older photog recently told me that the best time for pictures is 2-3 hours after noon or before sunset, with higher dr, I can make use of the whole day.


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## weixing (Sep 27, 2014)

Hi,
One think I don't understand is that how a camera can have more than 14 stops of DR when the camera only record in 14-bits... when you record in 14-bits, shouldn't mean that you should have a maximum of 14 stops and not more than that?? Or they don't record that data in a linear way??

Have a nice day.


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## epsiloneri (Sep 27, 2014)

weixing said:


> One think I don't understand is that how a camera can have more than 14 stops of DR when the camera only record in 14-bits...


What camera does that? Detectors sometimes become non-linear near the saturation limit, but the A/D conversion is usually linear, AFAIK.


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## serendipidy (Sep 27, 2014)

Maybe a dumb question, but what is/was the DR of film (such as Kodak ASA 100 or similar)? Was it better or worse than today's DSLRs?


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## jrista (Sep 27, 2014)

weixing said:


> Hi,
> One think I don't understand is that how a camera can have more than 14 stops of DR when the camera only record in 14-bits... when you record in 14-bits, shouldn't mean that you should have a maximum of 14 stops and not more than that?? Or they don't record that data in a linear way??
> 
> Have a nice day.



It's a conversion from decibels. Downsampling averages noise out. It's like binning or having larger pixels. So, if you start with a D810, with FWC of 78133e- and RN of 5.6e-. Your dynamic range is 20 log(78133/5.6), or ~83dB. Divide by six to get stops: 13.82. If you downsample, you average the read noise. Downsample by a factor of two, you average the read noise. It drops by a factor of the square root of the number of pixels averaged. A factor of 2 downsampling means you average 2x2 (4) pixels together, so your 5.6e- RN drops to 2.8e- RN. Your dynamic range is now 20 log(78133/2.8), or 89dB. That's 14.8 stops. 

For comparing cameras, this can be useful. You need to figure out a common size to downsample to for the cameras you are comparing, and calculate the read noise for each one at that specific size. DXO uses an 8x12" 300ppi print target as their common size. So long as you downsample to that exact size, then you could theoretically get more than 14 stops of DR. There are a number of factors with that...for one, you can't edit downsampled RAW images. Downsampling doesn't tell you how much DR the camera can capture in a single shot, either. Only the native DR tells you that. 

With a 14-bit ADC, the D810 has 13.8 stops of "hardware DR"...what the sensor itself is capable of actually capturing in a single shot. It gives you an idea of the editing latitude your going to have when pushing exposure around in a program like Lightroom. In the case of the D810, if your screen is an 8-bit screen (likely), then you have 13.8-8, or 5.8 stops worth of shadow lifting ability. Most Canon sensors, with ~11.5 stops of DR, have 11.5-8, or 3.5 stops of shadow lifting ability. (These would basically be absolute maximums with perfect circumstances...your probably going to get less than this in most cases.)

So, the CAMERA does not have more than 14 stops of DR. The IMAGE could be downsampled, which would result in more DR in the image. You can also apply regular old noise reduction routines, and accomplish the same thing...lower noise, more DR. If you want to obliterate high frequency noise in your images (noise at or very near pixel scale), you could buy PixInsight, and apply the TGVDenoise routine. That'll skyrocket your DR (assuming you don't have banding ). When publishing to the web, most people downsample, so you can generally assume that your final images that you upload to a web site somewhere are going to have lower noise/better DR (overall, not just in the shadows) than what comes out of the camera directly.


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## Marsu42 (Sep 27, 2014)

weixing said:


> One think I don't understand is that how a camera can have more than 14 stops of DR when the camera only record in 14-bits... when you record in 14-bits, shouldn't mean that you should have a maximum of 14 stops and not more than that??



To add to jrista's explanation: Magic Lantern uses 16bit in their dual_iso raw files because they merge 2x14bit. I don't know what resolution the 5d3's in-camera hdr raw files have, they've cut this feature from my 6d :-\


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## neuroanatomist (Sep 27, 2014)

Marsu42 said:


> I can shoot outdoors noon, with very bright sky and deep shadows or with the sun in the frame. An older photog recently told me that the best time for pictures is 2-3 hours after noon or before sunset, with higher dr, I can make use of the whole day.



I can use on-camera direct flash to light all my indoor and close outdoor pictures. Can doesn't mean should, though.


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## ajfotofilmagem (Sep 27, 2014)

serendipidy said:


> Maybe a dumb question, but what is/was the DR of film (such as Kodak ASA 100 or similar)? Was it better or worse than today's DSLRs?


The photographic film manufacturers do not disclose this information. Please correct me if I'm wrong, but from practical experience I can see that: 

Film type "slide" or "chrome" has less DR that any currently digital camera, but its wonderful color saturation leaves people mesmerized, and they do not care about black shadows and blown highlights. 

Film type "color negative" has gradation of tones unsurpassed and seem to have more DR than digital cameras. 

Film type "black and white" has DR really superior to digital cameras.


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## Marsu42 (Sep 27, 2014)

neuroanatomist said:


> Can doesn't mean should, though.



The rule still applies that soft light looks nicest, but for wildlife some critters simply do something else over the day and don't wait for the sun to give the photog optimal lighting. In these cases, more dynamic range means "thank the maker", as c3po would say.

Last not least, imho just like the 3:2 ratio (see a neighbor thread of mine) our eye is somehow tuned to think soft light + bokehlicious = good. But looking at old film slides, there are harsh contrasts, deep (but not infinite) dof, and these are still great shots just because they look different.


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