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: richard.lists at (Richard Man)
Date: Thu, 8 Oct 2009 12:15:17 -0700
References: <>

That may be true, but I am betting dollars to donuts that the cost of
blank does not account for the difference in end prices.

The low number manufactured is the prime reason, and because of that,
they can afford to use high level of tolerance and greater emphasize
on certain design goals (i.e. good performance even wide open), but
those are "side-effects." The main cause is still the simple
arithmetic of "they ain't going to sell many"

On Thu, Oct 8, 2009 at 11:26 AM, Doug Herr <wildlightphoto at> 
> 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.

// richard m: richard
// w: blog:
// book:

Replies: Reply from hopsternew at (Geoff Hopkinson) ([Leica] Zeiss Normal 50mm f/2 Planar T* ZM)
Reply from mark at (Mark Rabiner) ([Leica] Zeiss Normal 50mm f/2 Planar T* ZM)
In reply to: Message from wildlightphoto at (Doug Herr) ([Leica] Zeiss Normal 50mm f/2 Planar T* ZM)