Re: Primer on photographic exposure, etc.
Re: Primer on photographic exposure, etc.
- Subject: Re: Primer on photographic exposure, etc.
- From: Lars Borg <email@hidden>
- Date: Mon, 20 May 2013 15:58:44 -1000
Iliah,
Cameras serial numbers and lenses especially make a lot of difference,
Do you have a ballpark dE from unit to unit of same model for pro
gear? 5, 10, 20?
Using monochromator to shine the light onto the "bare" sensor and
through different lenses one can see how certain wavelengths are
getting attenuated heavily. Most of the canned profiles I built for
RPP are "no lens" profiles. It helps for metameric failure issues as
far as I can see.
So you're not calibrating the entire camera system (including actual
light, lens and polarizing filters) then?
I'm surprised you don't. Or am I misunderstanding you?
How big is the dE between your favorite lens on and off? Filter on
and off? I would assume BIG.
How do you compensate in your workflow for this dE?
The greatest and often overlooked problem is that profiles depend on
exposure, especially for saturated darker colours. It is a good idea
to make "bracketed" profiles, like for white patch exposed to 248
for normal exposure and -2 EV, -3 EV, -4 EV profiles.
Can you explain why that is? Non linear sensor? Wrong black level?
It seems counter-intuitive. (I assume constant exposure time,
constant temperature, or else the black level changes) 100 vs 200 vs
300 red photons (above black) should be same red (xy) regardless in a
RAW workflow.
Thanks,
Lars
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