[Alt-photo] f stop and log values

Keith Schreiber keith at jkschreiber.com
Fri May 26 18:44:15 UTC 2017

Bob - 

To reduce exposure by 1/3 stop, multiply by 0.79.

If you are interested in how this this figure is derived I'll explain it late. Gotta run now.


Keith Schreiber

> On May 26, 2017, at 12:05 PM, Bob Cornelis via Alt-photo-process-list <alt-photo-process-list at lists.altphotolist.org> wrote:
> I have a 31 step stouffer step wedge and need to know what fraction to
> increase/decrease exposure time when steps need to merge or separate.
> I know each step is 1/3 of a stop but wasn't able to find the corresponding
> fraction to adjust exposure. The Stouffer website has this info in the FAQ
> section for the 21 step wedge only.
> My math is not good enough to wade through all the equations on Wikipedia
> to get the answer!
> Thanks
> Bob
> -- 
> http://www.bobcornelis.com
> _______________________________________________
> Alt-photo-process-list | altphotolist.org

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