Re: [Leica] Why no ASPH teles?

["Dan Post" <dwpost@email.msn.com>]

I think that the reason you don't see aspherical teles is that they aren't
needed. The aspherical element is a boon to the wide angle lens designer in
that the focusing and light gathering requirements of the lens in the
extreme off-axis areas, read corners, is somuch different from the center
area, that a 'plain' spherical design lens would be un-necessarily
complicated, heavy, and expensive. From what I have seen of aspherical lens
elements, they correct and eliminate one or more correcting elements, hence
fewer inner reflecting surfaces, less flare, better color rendition, and
lighter weight.I even think some of these manufacturers are using high index
refraction plastic in their lenses too.
FWIW,
Dan'l
dwpost@msn.com
- -----Original Message-----
From: Lucien_vD <Lucien_vD@compuserve.com>
To: leica-users@mejac.palo-alto.ca.us <leica-users@mejac.palo-alto.ca.us>
Date: Monday, January 19, 1998 9:53 PM
Subject: Re: [Leica] Why no ASPH teles?

Mark wrote:

>I have been waiting a couple of years for Leica
>to launch an ASPH version of the 75 1.4 to match my Summilux,
>but so far no rumours.
>Any ideas?


Mark,

On page 230 of Leica, An Illustrated History, Volume II - Lenses
by James L.Lager,
there are 3 photographies of a prototype (or of a military ??)
75mm 1:2,4 Apo-Elmarit-M made in Canada nr 394-004.

Ok it's an APO and not an ASPH, and 2,4 instead of 1,4
but it should be ok.   :-)

Lucien
BELGIUM