Archived posting to the Leica Users Group, 1999/12/07

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Subject: Re: [Leica]revealing remarks (question to Erwin)
From: Eric Welch <ewelch@neteze.com>
Date: Tue, 7 Dec 1999 04:48:30 -0800

At 5:08 PM +0000 12/6/99, Dan S wrote:

>Is is more difficult to create an APO 50 than an APO 90? Would the benefits
>be the same for the smaller focal lengths in terms of real world
>performance?

The things that APO correction takes care of are mostly evident to a
significant degree (color fringing) occur in lenses of about 90mm and
longer. But aspherical correction works with wider lenses, but not so much
with longer lenses. Thus the only APO lens you will see that is also ASPH
is the 90.
- --

Eric Welch
Carlsbad, CA