Archived posting to the Leica Users Group, 1996/04/19

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To: leica-users@mejac.palo-alto.ca.us
Subject: Re: 100mm/2.8 R APO Macro question
From: Gang Huang <gang@mtdcr.mt.att.com>
Date: Fri, 19 Apr 96 11:52:42 EDT

At 12:21 AM 4/18/96 -0700, Eric Welch wrote:
>
>On the Apo Macro, it's not an "effect" in the sense that in the case of 
>the Leica it's not just changing focus the way all lenses do, it is 
>purposely designed to maintain performance by dropping about 8mm in 
>focal length as it goes down. Do the other lenses you mention vary that 
>much? Must be a basic design principle for macros if that's the case. 
>Interesting. Thanks for the info.
>
I do not own the lens but most lenses with floating elements do change the
focal length a bit when focus, especially at close distance at which the
floating elements "floats" more pronouncedly. 
 
---------------------------------------
Gang Huang
AT&T Bell Laboratories
200 Laurel Ave. 3B-216
Middletown, NJ 07748
U. S. A.
(908)957-3524
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