[rollei_list] Re: postwar changes
- From: Jerry Lehrer <jerryleh@xxxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Thu, 10 Nov 2005 21:23:04 -0800
Eric,
The "tarnish" is composed of oxides, sulfides etc. of some
of the metallic salts that are part of the sands that made the glass.
Unpredictable because various lens designs used different
glass types.
Jerry
Eric Goldstein wrote:
> Todd Belcher wrote:
>
> > Actually, there is a 'unclean' uncoated lens that is okay - and that is
> > when an uncoated lens acquires some tarnishing. H.D.Taylor, the inventor
> > of the Cooke Triplet, noticed that old tarnished lenses had higher light
> > transmission than newly pollished ones.
>
> Good point, Todd. DTH actually went quite a way down the road trying to
> develop a controlled tarnishing process to take advantage of this effect
> in commercial application...
>
> Eric Goldstein
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