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Microstock Photography Forum - General => Photography Equipment => Cameras / Lenses => Topic started by: davidm on February 03, 2009, 04:27

Title: Canon 5D MK II/1Ds MK III, Nikon D3/D3X/D700 full-framers - incorrect ISO?
Post by: davidm on February 03, 2009, 04:27

I found quite an interesting article by Mason Resnick, formerly Popular Photography Managing Editor and now an Editor in Adorama Learning Center.
Cutting the long story short, Mason is sure that all 6 currently available full framers display incorrect ISO, with 1/4 up to 1/2 (!) step underexposure.

I tried to summarize his lab results in the table here (http://blog.prostockmaster.com/2009/01/30/canon-5d-mk-ii-nikon-d700-nikon-d3-nikon)

The thing that I especially loved was the test of Nikon D3X @ ISO 50 which led to the conclusion that ISO 50 at D3X is in fact an in-camera noise-reduction post-processing, i.e. "not a real thing"

For APS-c size sensor bodies Canon 40D was measured with 1/3 underexposure for all ISO speeds. Should I apply a permanent exposure compensation for my 40D now?

Title: Re: Canon 5D MK II/1Ds MK III, Nikon D3/D3X/D700 full-framers - incorrect ISO?
Post by: Freezingpictures on February 03, 2009, 05:29

I mostly have my camera settings on my 30D on 1/3 overexposure, so what he wrote makes sense to me..

Title: Re: Canon 5D MK II/1Ds MK III, Nikon D3/D3X/D700 full-framers - incorrect ISO?
Post by: boatman on February 03, 2009, 06:51

I normally have my 40d at 1/3 or 2/3 over, so it seems he may be right

Title: Re: Canon 5D MK II/1Ds MK III, Nikon D3/D3X/D700 full-framers - incorrect ISO?
Post by: vonkara on February 03, 2009, 10:53

I'm always 2/3 and even 1L over with my D300. But the 0 exposure is gray. That mean it's not necessarily the perfect exposure I think. Only the exact middle between perfect black and perfect white

Title: Re: Canon 5D MK II/1Ds MK III, Nikon D3/D3X/D700 full-framers - incorrect ISO?
Post by: ichiro17 on February 03, 2009, 10:57

Its the one thing I agree with DxOMark about.

All the cameras have different results when you put the ISO to 100, put them same lens on all of them and shoot the same picture with the same shutter speed and aperture.  This can only be to the misrepresentation of the actual speed of the sensor.

Its crap, because we all know that ISO is a standard, but its just a way for the marketers to market their 6400 ISO and other crap.

There is nothing you can do about it but compensate.  Unfortunate

Title: Re: Canon 5D MK II/1Ds MK III, Nikon D3/D3X/D700 full-framers - incorrect ISO?
Post by: louoates on February 03, 2009, 16:53

The only thing I believe is the histogram.

Title: Re: Canon 5D MK II/1Ds MK III, Nikon D3/D3X/D700 full-framers - incorrect ISO?
Post by: alias on February 04, 2009, 03:30

Quote from: louoates on February 03, 2009, 16:53

The only thing I believe is the histogram.

I think that the histogram show data for the internal camera processed embedded preview rather than for actual raw data. That used to be typical I think. Result being that we can not believe the histogram displayed on the back of the camera because of the internal processing applied to make the preview. This issue is very well documented on camera tecknical forums. Problem may have been addressed in later models. In the end you can only trust your spidey-senses.