# Does ISO affect Dynamic Range?



## ismael (Jul 13, 2009)

Hello,

   Isolating the topic of Dynamic Range: is it affected by ISO sensitivity?  
In other words: If a sensor has a DR of say 8 stops, would that be across the entire ISO range? 
 How about in film? Let say Kodak Gold 100 and 400: Would the DR be totally unrelated to speed?

Thanks,


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## GeneralBenson (Jul 13, 2009)

I'm pretty sure that you lose DR ans the ISO gets higher.  I'm not sure about this, but I'm pretty sure, nor do I know to what degree you lose DR.


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## Big Mike (Jul 13, 2009)

Interesting question.
As far as I know, ISO does not affect the dynamic range with digital.

What ISO does affect is noise levels...and another thing that affects noise is exposure, so I'm thinking that the two could be related.  For example, you might get a nice dynamic range and a clean shot at ISO 100, but at ISO 3200, you might have the same exposure range, but now the shadow areas are too noisy.


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## KmH (Jul 13, 2009)

Yes, an interesting question.

Have to add that to my list of things to research but off the top of my head I'd say no, it's a function of the image sensor.

Trouble is, performance at high ISO has a lot to do with the quality and performance of the amplifiers.


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## Baaaark (Jul 13, 2009)

Nikon D300 Review: 20. Photographic tests: Digital Photography Review

http://www.dpreview.com/reviews/NikonD300/Samples/DynRange/iso.png

BTW I don't know how or why it does affect range, but it does.  And not always in the way you'd think.

This also may not be the case with film.


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## Moglex (Jul 13, 2009)

I would say definitely yes.

As you increase the ISO the noise level increases.

This *must* swamp the most subtle differences in level particulary in the deep shadows.

Thus the dynamic range is reduced.


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## AlexColeman (Jul 13, 2009)

Yes, according to DXO Labs :D700


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## Clawed (Jul 13, 2009)

I believe I read somewhere recently that ISO does indeed affect dynamic range.  If I can locate the source, I will post it here.


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## usayit (Jul 13, 2009)

Definitely....  At really high ISOs (1600+) it can be as little as 2 stops (depending on the camera).


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## JerryPH (Jul 13, 2009)

Raising ISO *does* make you loose dynamic range.  Thom Hogan in his book discussed this in detail.

Going from ISO 200 to 1600 gives you a loss of 1.5-2 stops of dynamic range on the D700.  It is closer to 3.5 stops on a D200.  Other cameras will give you the same or greater range losses.

This is one of those questions where if you take 5 minutes and try it out yourself, it becomes evident.  Take a low light shot at ISO 100 and a longer shutter speed.  take the same shot at higher ISO and faster shutter speed.  Note the obvious differences in the shadow details.

This is using a RAW file, becuase it has the most dynamic range of any digital format.


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## ismael (Jul 13, 2009)

Thanks for the responses!
Jerry, I DID try it. That's why I was asking. :er:

Thanks,


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## musicaleCA (Jul 13, 2009)

JerryPH said:


> This is using a RAW file, becuase it has the most dynamic range of any digital format.



*cough* Except for Adobe's Radiance format *coughcough*


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## tsaraleksi (Jul 13, 2009)

One more thing to remember is that if you use a 'boosted' ISO, usually one that is listed as High/High 1/2, or whatever, you're going to be losing quite a bit of DR because it's actually pushing the image by a stop or two to get it to that ISO rating.


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## JerryPH (Jul 13, 2009)

musicaleCA said:


> JerryPH said:
> 
> 
> > This is using a RAW file, becuase it has the most dynamic range of any digital format.
> ...



*cough* my D700 doesn't make Adobe's Radiance format files and you cannot add detail or dynamic range to a file once it is created  *cough*


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## AlexColeman (Jul 13, 2009)

I believe my link solved the debate.


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## JerryPH (Jul 13, 2009)

ismael said:


> Thanks for the responses!
> Jerry, I DID try it. That's why I was asking. :er:



Then your answer was in front of you, and you did not catch it.  I bet you likely did not check at 100% file size, thats probably why it was not obvious immediately.  I know it was for me when I did this test last year after reading about this in the D700 PDF book by Thom Hogan.  It was especially obvious when I did the test on my D200.


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## ismael (Jul 13, 2009)

Good  for you!


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## JerryPH (Jul 13, 2009)

... and now you have your answer.  

What I cannot tell you is if this effect is exactly the same in film.  I would have to say in my more limited knowledge of film, that the effect would be there, but less so.  Film has increased DR over any digital camera on the market to date (12 stops with film, around 9 stops using a D3x), so, whatever was lost (if any), the final results would still be better using film vs digital files.


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