LaFonte: But why do I even have to care about equivalent or not exposure? If I say to two guys don't use your camera metering, pull out my old light meter and tell to two guys with very different camera: set your ISO 100, set 1/60, and aperture 2.2 and you will be fine, they would both get properly exposed picture. Right? Even that one geezer have 7d and the other have e-pm.As I understand, that is the whole point of having equivalent exposure that translates to everybody. So we understand each other without looking what size of sensor you have. Starting recalculating what aperture means in different sensor sizes is good only and only for assuming DOF not for exposure.So maybe call it equivalent DOF.Or is it that I totally don't get it?
@quezra" larger sensors have less signal-to-noise ratio than smaller sensors"
You might want to think about what the expression "signal-to-noise ratio" means and then edit your comment accordingly.
I think what's missing from the ISO discussion is how the image is going to be used. If you're shooting primarily for the web, the size reduction process is going average out so much of the noise that except for at really high ISOs, any FF advantage over a smaller sensor is going to be imperceptible. The same applies to a lesser extent with, say, 4" x 6" 240 DPI prints.
Although it touched on it, the article could have emphasized more that, unlike, say, f-stop equivalency, which is purely mathematical, ISO equivalency is very much affected by physical properties, sensor fabrication technologies etc. and is distinctly nonlinear across the ISO range. After all, if we had "ideal" sensors that generated 0 noise across the whole ISO range, the concept of ISO equivalency wouldn't even exist. There's no similar "ideal" scenario for f-number equivalency.
nigelht: Total light is meaningless to noise. Given the same FOV then the total light will be the same. Given different FOVs with the same intensities (as in the example provided) then for the same sensel size then the same number of photons hit so shot noise is identical since the photon shot noise is the square root of the number of photons on a per sensel basis.
Read noise is more dependent on the sensor design and generation but there is a minor advantage for larger sensor since the base SNR for FF sensors is typically slightly better than m43 or 1" of the same generation. Mostly though the noise is dominated by shot noise.
All you've shown on your example charts is the effects of larger sensel size.
The sensel (pixel) sizes for the cameras listed are:
EOS 1-DX : 41.45 um^2X-A1: 22.66 um^2GH4: 13.99 um^2V3: 6.3 um^2
The area of each EOS 1-DX sensel is 658% larger than a sensel on the Nikon 1 V3.
The 1-DX sensel area is 111% larger than on the X-A1.
"When you crop a 36MP FF sensor to APS-C proportions, you get 16 MP. Are you saying that according to your sensel size only theory, that 16 MP APS-C sensors should be giving equivalent results to FF?"
Well, I'm not, necessarily, but DP Review seems to be:
Of course, if you *scale* a 36Mp image down to 16Mp, its noise figure will improve relative to a 16Mp sensor showing the same scene, but that's not what you seem to be saying.
HoustonPowers: I have a small bug in Lightroom 4. When I mouse over the histogram in the Develop Module, the pop up tips are E-mail labels, such as "Mark as read", "Mark as spam" "delete", "reply"..etc..Anyone else have this happening to them?Just curios if its just my system. Its a peculiar bug.
That IS bizarre, then! It's hard to imagine how those strings even appear in LR (or any Adobe program, come to that). I'd be interested to know if those tool tips are the same as the ones in whatever mail program you use...
Those tool tips most likely come from the app *under* LR. It might still be a bug in LR, but could also be a problem with Windows, or even the application underneath.