I would expect that to be true of all digital cameras as exposure
(luminance) is taken only from the 2 green pixels (each interpolated
pixel is made up of two green and one each red and blue) which most
closely match the response of the human eye.
(Disclaimer: the above is vastly simplified, if you want a detailed 5
paragraph explanation someone else will be glad to supply it)
graywolf
http://www.graywolfphoto.com
"Idiot Proof" <==> "Expert Proof"
-----------------------------------
Charles Robinson wrote:
On Nov 30, 2005, at 13:11, Glen wrote:
I've been told that a lot of DSLR cameras use only the green channel
when calculating the histogram, instead of the full RGB data. Does
the Pentax *istDS display a true RGB histogram, or not? It seems
that there have been times when the histogram hasn't been entirely
accurate for me. I got clipped highlights sometimes when the
histogram didn't suggest any such thing.
Sounds like something that could be checked by taking a full-frame
photo of something that is entirely blue, entirely red, and entirely
green. Assuming the metering is about 18% grey for all 3 targets, I
would expect the histogram (if monochromatic) to look wildly
different between the 3 photos.
(with the understanding that the idea of "pure" green/red/blue
targets is more theoretical than achievable, but it should be close
enough to get the idea, doncha think?)
-Charles
--
Charles Robinson
[EMAIL PROTECTED]
Minneapolis, MN
http://charles.robinsontwins.org
