Archived posting to the Leica Users Group, 2003/02/13

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Subject: Re: [Leica] Re: Hexar RF Back focus one more time
From: Dante Stella <dante@umich.edu>
Date: Thu, 13 Feb 2003 22:58:41 -0500

Dead wrong.  A fast wideangle at infinity, like a 21/2.8.  That is 
where if you have any error in back focus, you will focus in front of 
or behind infinity.

The closer the lens is focused, the more depth of focus due to 
increased magnification.

Wideangles gain depth of focus to a much lesser degree as you focus 
close.

There is a very detailed description of this on my web site.

On Thursday, February 13, 2003, at 10:24 PM, Don Dory wrote:

> John, I think that the more critical test would be a fast wide angle 
> at near
> minimum focus.  Why, you ask?  While a wide angle has more DOF the 
> distance
> from the rear element to the film plane is extremely critical, more so 
> than
> a telephoto:  therefore if the film plane is off the lens won't be 
> sharp.  I
> should know, I have some issues with a 35 Biogon on a Contax.
>
> Don
> dorysrus@mindspring.com
>
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>
____________
Dante Stella
http://www.dantestella.com

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Replies: Reply from "Don Dory" <dorysrus@mindspring.com> (Re: [Leica] Re: Hexar RF Back focus one more time)
Reply from Stephen Gandy <leicanikon@earthlink.net> (Re: [Leica] Re: Hexar RF Back focus one more time)