Archived posting to the Leica Users Group, 2001/01/17

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Subject: RE: [Leica] Re-computer 50mm Summilux-M
From: "Rodgers, David" <david.rodgers@xo.com>
Date: Wed, 17 Jan 2001 14:54:36 -0600

Pascal

>>why would these lenses need an aspheric element to deliver top-notch
performance???

even the newest Summilux-R 50/1.4 did not need such element.<<

I wonder if this is really and apples to apples comparison. Modern aspheric
elements are pressed (molded) not ground. (Though amazingly, I believe the
asphericaL elements were ground in the original 35/1.4 Aspherical). I also
believe in most cases aspherical elements are pressed from plastics, not
glass. Somebody please correct me if I'm wrong. 

There are limits on manufacturing aspheric elements. The bigger the element
the more difficult to manufacture. Don't know if there's a theoretical limit
on size, but I know there's a practical limit, particulary in terms of cost.
Aspheric elements may be practical to use in an M lens, and not in an R
counterpart. 

Dave

Replies: Reply from Dan Cardish <dcardish@sympatico.ca> (Re: [Leica] Re-computer 50mm Summilux-M)
Reply from "Stefan Kahlert" <S.Kahlert@gmx.de> ([Leica] A question for users of the 1,4/35 pre-asph.)