Archived posting to the Leica Users Group, 1996/04/17

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Subject: Re: 100mm/2.8 R APO Macro question
From: Bill Christensen <>
Date: Wed, 17 Apr 1996 03:14:16 -0500
References: <>


The Elpro (catalog no. 16545) for the 100mm R APO lens provides a 
continuous focusing range from 1:2 to 1:1.1.  While the maximum aperture 
remains 2.8, a very slight light loss may occur due to the added glass. 
 If it exists, it has not presented a problem nor does it require a 
special calculation.

As a footnote, I have also employed the 100mm lens, Elpro plus one or 
two Macro-Adapter-Rs for images closer than 1:1.  It works like a charm 
with a solid tripod and mirror lock-up.  One Leica technical guru 
stated, however, that an increase in the distance between the rear lens 
element of an APO lens and the film plane will diminish image quality.  
If so, I have not seen it in terms of color vibrancy and image 
sharpness.  You will, of course, lose one-half f-stop for each 
Macro-Adapter-R that is used.   

Bill Christensen
Bill Christensen

Replies: Reply from Eric Welch <> (Re: 100mm/2.8 R APO Macro question)
In reply to: Message from (Roger L. Beamon) (Re: 100mm/2.8 R APO Macro question)