On Mon, Dec 29, 2003 at 07:35:16PM -0500, Herb Chong wrote:
> did you shoot in RAW? if you did, you could convert to TIFF with exposure
> compensation of -1 and gotten more out of the *istD. that's how the camera
> works and one of the reasons why i shoot RAW unless i have no choice. it
> gives me one more stop to play with before the highlights saturate.
Yes, I did, I always do.
If I wasn't shooting RAW, the highlights would have saturated at 255, and
not at 4095, as I said.
I'm not sure whether RAW actually gives you one more stop of dynamic
range/sensor acceptance range. That might be an impression created by the
Pentax software, which I do not use (I use Linux, dcraw, cinepaint, and
gimp 1.3).
It is plausible that, when shooting JPG, that the JPG is derived from the
entire dynamic range of the RAW (i.e. RAW 0 -> 4095 is mapped to
JPG 0 -> 255) - but of course there are less gradations of tonality
inbetween in the JPEG. I think the black point and the white point of the
JPEG are chosen based on a combination of thumbsuck, heuristics, the shape
of your histogram, and your contrast setting, and it need not be true that
there is an extra stop available either below the black or above the white
of your JPEG. Sometimes, but not always.
However, even in those cases, should you choose to only use the rightmost
2/3 range of your exposure, you can do that with RAW and it's finer
gradation of tonality, without posterisation.
How does the RAW -> JPEG conversion of the Pentax software compare to what
happens in-camera? If it is similar, I could do some experiments to see
exactly how the dynamic range of the RAW and the JPEG relate.
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