[APML] Film Thickness and Focusing

["Thom Iwancio" <tiwancio@sc.rr.com>]

Hey all, getting tired of the "by guess, by golly" focusing method but
lacking the funds for a real focus aid I have been researching the
various homemade knife edge and ronchi screen focusers.  

My question is what is the depth of focus(field?) for an 8" f6
combination?  I ask because today I took some film to work and measured
the thickness of the leaders using some precision gauging in our quality
lab. My results were:
Elite Chrome 100		.0061
Elite Chrome 200		.0062
Old (good) Supra		.0060
Tech Pan			.0040

Do I need to create a set of shims for the difference between Elite
Chrome 200 and Tech Pan?  These are my two primary films.

As always, thanks in advance.

Thom Iwancio
Elgin, SC
www.machunter.org


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