Archived posting to the Leica Users Group, 2009/10/08

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Subject: [Leica] Zeiss Normal 50mm f/2 Planar T* ZM
From: wildlightphoto at (Doug Herr)
Date: Thu, 8 Oct 2009 14:26:53 -0400 (EDT)

Frank Filippone wrote:

>Makes no difference to the cost of the blanks.  A chunk of glass of type ABC
>is the same, regardless of the grinding yet to be done on it.  Yes, the cost
>of making those blanks into a finished lens element may/could/probably is

Company A can specify glass type ABC with tolerances for refractive index 
+-0.2% dispersion +-0.25% surface hardness +-0.3% expansion coefficient 
+-0.7% and company B can specify the same glass type with tolerances 1/2 of 
company A's requirements and I'll bet company B's glass blanks are gonna 
cost more and the finished lenses will show a lot less sample variation.

Doug Herr
Birdman of Sacramento

Replies: Reply from mark at (Mark Rabiner) ([Leica] Zeiss Normal 50mm f/2 Planar T* ZM)
Reply from richard.lists at (Richard Man) ([Leica] Zeiss Normal 50mm f/2 Planar T* ZM)