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: hopsternew at (Geoff Hopkinson)
Date: Fri, 9 Oct 2009 07:11:59 +1000
References: <> <>

That rather misses the point though Richard.
To assist in achieving those design goals, some of those blanks are from
extremely expensive and exotic glass types.
Grinding and inspection is done one element at a time by extremely skilled
operators. Assembly into the intricate all metal mounts is entirely by hand
which themselves are expensive  and made to tolerances of 1/100th of a mm.
Example of important contributor to Leica lens excellence

2009/10/9 Richard Man <richard.lists at>

> 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 
> wrote:
> >
> > 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:
> _______________________________________________
> Leica Users Group.
> See for more information

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