Archived posting to the Leica Users Group, 2005/06/15

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Subject: [Leica] Re: darkroom focusing
From: kanner at (Herbert Kanner)
Date: Wed Jun 15 19:18:12 2005

I think focus shift is a myth. If the focus were to shift when 
stopping down, this would indicate that spherical aberration is so 
poorly corrected that the portion (a ring) of the lens that is active 
between say f/8 (the enlarging aperture)and say f/2,8, the focusing 
aperture, has a marked;y different focus distance than the portion (a 
circle) from the center to the periphery at f/2.8.  If this were 
true, the lens would suck; it would be noticeably fuzzy at f/2.8.

Herbert Kanner

Do not meddle in the affairs of cats,
for they are subtle and will pee
on your computer!

Replies: Reply from feli2 at (Feli) ([Leica] Re: darkroom focusing)
Reply from henningw at (Henning Wulff) ([Leica] Re: darkroom focusing)