Heck I gave you all +1's! I think all the arguing back & forth is great, as there is a lot to learn/understand! As long as we're civil about it
I have a # of questions, especially for LTRLI, neuroanatomist, & jrista:
(1) If Canon claims quantum efficiency is up due to better microlens design, and if initial tests show better ISO performance for the MkIII vs the MkII with RAW files (i.e. no influence of noise reduction, hopefully), then doesn't all that mean that SNR is necessarily
higher? And doesn't higher SNR necessarily
mean greater DR, for the same general sensor design (assuming nothing actually got *worse* btwn the MkIII & MkII)? Am I missing something here?
(2) Let's say those masked pixels really are sealed/blocked off from light OR are somehow turned off. However, let's say they're still being read by the electronics & so they can still be an indication of dark noise. Then, you use:Equation 1:
DR = log(base 2) [highest signal/stdev]
But for that calculated DR to be indicative of the max possible DR of the scene being recorded -- doesn't that presuppose a linear relationship between incoming light & recorded signal in the RAW file? Do we know this to be true?
(3) Related to question (2)... Has anyone actually established that Equation 1
is a standard, accepted, measure of DR? DXO says "Dynamic range is defined as the ratio between the highest and lowest gray luminance a sensor can capture
"... note it doesn't say "... a sensor records
". Again, assuming a linear relationship between incoming light & signal recorded (which is not
true, for example, for film) in the RAW file, I guess this'd be the same. But but from DXO's testing methodology description (http://www.dxomark.com/index.php/About/In-depth-measurements/DxOMark-testing-protocols/Noise-dynamic-range
), I thought they were using actual light source/ND filter combinations to measure the SNR & DR.
(4) I must say I find it strange that in DXO's methodology in the link above, they state that they use a setup "in order to test across a dynamic range of 4 density steps (= 13.3 f-stops — a dynamic range much greater than today’s digital cameras)"... but then report that the Nikon D7000 has 13.9 stops of DR. Is this just an outdated description?
Thanks in advance!