Originally posted by falconeye Well, I understand everything about a histogram in a photo editor.
A photo editor histogram is the so-called images's N-Bit Histogram and has a linear scale, where the f-stop scale is logarithmic. There are no "middle parts" behaving differently.
I see two choices:
- The sensor doesn't capture luminosity linearly (a bad thing to be compensated by tone mapping -- so one should know about).
- The Pentax back LCD histogram isn't a photo editor's 8-Bit histogram.
I will investigate this and report my findings as soon as I have them. Thanks for the responses so far.
You need to take a close look, and plot in 'stops" not FStops i.e. 1, 2, 3...
if you do this you will see the histogram is linear over about 5 stops in raw, with compression at both ends.
If you want to go by "F-Stops", then of course beause the F stop is a log scale, it is not linear, but if you just count in stops or EV , then for an extended portion of the middle range the histogram is perfectly linear with each stop. DO the test and see for your self