[Leica] Re: Titanium lenses: Summicron ASPH low production

[lambroving at worldnet.att.net (William G. Lamb, III)]

Frank,

Correct me if I'm wrong, but I believe several sources state that the 28 
ASPH also has a ground aspherical element. It is currently my fave. That 
first 35 Lux ASPH is pretty rare, isn't it? Do you know how many were made? 
It might be a plus that the 50 ASPH now has a ground Aspherical surface. 
Wonder whether it's true. Irwin's initial review stated that the element is 
pressed.

William

At 09:37 AM 11/07/2004 +0000, you wrote:
>Hi Sander,
>I did check whether this new batch of titanium stuff was still a coating 
>or not. It states explicitly on the Leica website that the limited edition 
>is made with solid titanium not a coating.
>I had not read that the Asph surfaces are no longer pressed. I know the 
>asph surfaces for the f1.2 Noctilux and original 35mm f1.4 Aspherical 
>(which is my most used lens BTW) were ground and the scrap was rate high. 
>I know that the immediately subsequent asph surfaces were hot pressed. I 
>had heard that there were problems pressing the asph surface for the 90 
>AA, but had not heard they had reverted to a ground surface. I had not 
>heardl that any recent lenses were ground aspherics. The "mass" production 
>of ground aspherics is certainly feasible now as they are used on the 
>larger elements in Canon aspheric lenses, but AFAIK grinding is only used 
>when the element is too big for hot pressing.
>I believe that the 35-70 f2.8 was dropped because it proved uneconomic to 
>make to the desired tolerances, was this a problem with aspheric surfaces?
>Frank