snapsy wrote:
That photo is great on so many levels but it's the tones that really stand out.
Thanks for that. I have a 20 x 30 copy hanging on a temporary basis in my office, and I was looking at it earlier today. Your comment about the tones reminds me of something that I observed about part of what makes it work. There is something about the light in the scene that I recognized but couldn't quite describe, but today I realized (the obvious, perhaps) that the lower half of the frame holds tones that go all the way from black (in a very small areas) to a few essentially pure white highlights, but as the scene recedes toward the distant bridge, the extreme tones are gone and it is mostly mid tones.
The ISO calibration from DXOMark is a calibration of the true light sensitivity, that may differ from the manufacturer's specification, but has nothing to do with how the amplification is implemented. All cameras differ somewhat form the spec there.
You cannot really separate the selection of ISO from how you expose with respect to the histogram and clipping. When you select ISO 160 on the 5DII, you get less headroom, and you could have gotten the same good results for pattern noise by exposing to the right with ISO 200. But you would still clip the maximum signal from the sensor compared to ISO 100, so using ISO 160 will not give you the lowest possible photon shot noise even if you expose to the right there.
ISO 160 is a kind of a lazy way to expose +1/3 at ISO 200. If there was a setting for ISO 80, it would have been a nice lazy way to expose +1/3 at ISO 100. ...Show more →
yeah 160 and 200 are basically the same thing just with hidden +/- 1/3 stop exposure change, they have the exact same DR
although since banding noise pops out to the eye more the DR of ISO160 (or ISO200 exposed 1/3 longer) might look a little bit higher to the eye and not quite the same as that from ISO200 straight.
ISO100 still exposes things longer so you collect more photos than ISO160 or 200 and it typically has the same to the tiniest smidge higher DR (not that you'd ever be able to really tell such a tiny difference) than ISO160/200 but it does mean a deep look into shadows where banding may be even more apparent...
some people prefer tossing banding a touch deeper into the shadows at the expense of 2/3 stops more noise across the range and like ISO160/200 over ISO100, it depends
40D and 1Ds3 too I think tend to handle HTP mode pretty well since they have relative low low ISO banding
