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F-stop and linear tonemapping

Posted: Mon Aug 10, 2009 11:02 pm
by Jambert
I've made lot of test and I don't understand why but F-stop and linear tonemapping give change tonemapping!? Is it right?

Re: F-stop and linear tonemapping

Posted: Mon Aug 10, 2009 11:56 pm
by fused
its correct. the lower the fstop the more light will reach the film :)

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 12:22 am
by Jambert
fused wrote:its correct. the lower the fstop the more light will reach the film :)
Thanks :)

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 1:26 am
by PureSpider
But it hasn't been like that in older releases of indigo. What about not changing random stuff without letting the user know, Ono? :roll:

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 1:38 am
by pixie
PureSpider wrote:But it hasn't been like that in older releases of indigo. What about not changing random stuff without letting the user know, Ono? :roll:
If it wasn't as such before, it was wrong, therefore changing to right can only be the right thing to do ;)

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 1:45 am
by fused
of course it was like that before. it has always been like that :)

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 1:59 am
by PureSpider
Sooooo... Cindigo compensates the changed F-Stop? o.O
My pics never changed their brightness when I changed the F-Stop! :shock:

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 2:04 am
by Josh
Tonemapping (other than linear) masks the change of illumination, I suppose.

Edit: Camera tonemapping without auto exposure (and no manual exposure adjustment) should not compensate.

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 2:05 am
by fused
probably because you used reinhard ;)

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 2:12 am
by PureSpider
Just checked - and yes, I do use Reinhard in that scene I was talking about :oops:

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 5:38 am
by CTZn
Hey Jambert, I think the topic deserves a complement of information, but I am no expert in the field, hopefully my says will be also completed or corrected if necessary.

F-stop is an inverse value (1/n) wich refers to the width of the aperture for the shutter. Obviously, the bigger the divider n, the smaller the aperture.

F-stop = divider of aperture = divider of luminosity


Q: Is it correct to say that an F-stop of 32 means that the shutter aperture is 1/32th of its widest possible aperture?

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 6:05 am
by dougal2
CTZn wrote:Q: Is it correct to say that an F-stop of 32 means that the shutter aperture is 1/32th of its widest possible aperture?
Not quite, it means that the aperture is 1/32 of the focal length.... which is why low f-number telephoto lenses (large focal length) are expensive and massive - because the glass needs to be bigger.

Re: F-stop and linear tonemapping

Posted: Tue Aug 11, 2009 6:19 am
by CTZn
Ah, thank you Doug ! I got it all wrong :P