Archived posting to the Leica Users Group, 2005/02/11

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Subject: [Leica] Re: FS: Leitz/Leica 350mm f/4.8 Telyt-R
From: Frank.Dernie at btinternet.com (Frank Dernie)
Date: Fri Feb 11 00:22:04 2005
References: <20050211013003.49678.qmail@web81204.mail.yahoo.com>

AFAIK there is no such thing as "APO glass". To get APO performance a 
combination of elements of differing characteristics and curvature is 
required to cancel the fact that different colours diffract 
differently. The unusual partial dispersion glasses which this requires 
in at least one element are very expensive. Whether the 350 actually 
has these is debatable. The fact that it is v. sharp is well documented 
:-)
Frank


On 11 Feb, 2005, at 01:30, SEUNG MIN LEE wrote:

> I have never heard that it had APO glass


Replies: Reply from jcb at visualimpressions.com (JCB) ([Leica] Re: Re: FS: Leitz/Leica 350mm f/4.8 Telyt-R)
Reply from jcb at visualimpressions.com (JCB) ([Leica] Re: Re: FS: Leitz/Leica 350mm f/4.8 Telyt-R)
In reply to: Message from leirex at sbcglobal.net (SEUNG MIN LEE) ([Leica] Re: FS: Leitz/Leica 350mm f/4.8 Telyt-R)