[rollei_list] Re: OT: Xenar

  • From: Eric <egoldste@xxxxxxxxx>
  • To: <rollei_list@xxxxxxxxxxxxx>
  • Date: Fri, 23 Sep 2005 17:31:36 -0400

Richard Knoppow:

> I think yor are refering to five element Tessar type
> lenses rather than the Xenotar type, which was based on work
> done by C.G.Wynne of Wray in England. Wray's work was done
> c.1944.
> The Xenotar is, essentially, a modification of the Biotar
> type where two elements are combined into one. The lens
> still has the essential symmetry of the Biotar. There were a
> number of Tessar type lenses with three cemented elements in
> the rear, Schneider made at least one. Zeiss had a 6 element
> Tessar called the Biotessar with three cemented elements in
> back and two in front. I suppose it could also be considered
> a Heliar type. Bausch & Lomb made an arial lens with three
> cemented elements in the rear, other lenses were the Ross
> Xpres (not the W.A.Xpres, which is a Plasmat) and the
> Gundlach Radar. The Radar was probably designed to avoid the
> Zeiss Tessar patent rather than to improve the correction.
> In any case, the idea of adding an element was tried by
> several makers. It would seem that other designs were more
> successful in providing improved performance.
> 
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@xxxxxxxxxxxxx


The Xenon as used on most Retinas is a 6 element Opic variant (mostly
symetrical double-gauss), a pre-was design (at least the f/2 variants).


Eric Goldstein

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