Re: [Rollei] Search for highest 5 element Planar -- how about Tessar

["Richard Knoppow" <dickburk >]

- ----- Original Message ----- 
From: "Fox, Robert" <RFox  >
To: <rollei  
Sent: Wednesday, April 30, 2003 11:01 AM
Subject: RE: [Rollei] Search for highest 5 element Planar -- 
how about Tessar


> Hey,
>
> I've been deleting all the posts on the Planar debate
since I don't own
> a Planar, but how about a *quick* explanation of Tessar
and Xenar
> history for those of us who know next to nothing about
Zeiss or lenses
> but are curious nonetheless?
>
> TIA,
> R.J.
>
  The best single source of lens history is:
_A History of the Photographic Lens_ Rudolf Kingslake, The
Academic Press.

  The Tessar was invented by Paul Rudolph of Zeiss. It was
derived from his earlier Protar lens. The Protar was the
first commercial lens to make use of the high index glasses
developed by Schott in the mid 1890's. The Protar, which had
two cemented components, each of two elements, was not
entirely satisfactory so Rudolph modified it by converting
the front component to an air spaced group. This lens had
very good performance. It was patented in 1902 originally as
an f/8 lens.
  Faster versions were rapidly developed at Zeiss by Merte
and others.
  Nearly every lens manufacturer has made Tessar type
lenses. In the USA Bausch & Lomb made them under contract to
Zeiss.
  I don't know the date the Schneider Xenar was first
produced but it would have been sometime after the Tessar
patent expired, about 1918. It is not an exact copy of a
Tessar, none of the myriad of Tessary type lenses is, but it
is based on the same design concept. There are a number of
patents issued to Schneider for improved Tessar type lenses.
Some of these designs were by Tronnier, who also designed
lenses for Voiglander.
  Among the best Tessar type lenses ever built are the Kodak
Commercial Ektar series.
  Currently, Nikon makes an f/9 Tessar for large format
cameras of excellent design.
  Probably more Tessar type lenses have been built than any
other type other than simple meniscus lenses as used on
simple box cameras.
- ---
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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