From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 06/02/03-05:10:33 PM Z
----- Original Message -----
From: "Tor-Einar Jarnbjo" <tor-einar@jarnbjo.de>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Monday, June 02, 2003 3:47 PM
Subject: RE: Age of Rodenstock lens
>
> > I am confused. I've received mail from two sources
> > evidently about the same lens. This seems to be another
> > lens, is it? Who is the manufacturer?
> > I don't find the name Bistigmat in a quick search, not
> > listed as a Rodenstock name although they made a
Biplanat.
> > The "stigmat" part of the name suggests an
anastigmatic
> > lens, if so, this would indicate it was made after the
> > development of "Jena" glass in 1885. While it is
possible to
> > make an chromatically corrected anastigmatic lens with
"old"
> > glass this was not known until long after the new Barium
> > crown glasses were introduced. The Busch Omnar, designed
by
> > Martin, a four element air spaced lens of the
"Homocentric"
> > type is made with all old type glass.
>
> It is a brass lens with the following inscription:
>
> No 37023
> Bistigmat 13x18
> Rodenstock München
>
> I don't understand Hungarian, but at least you find
pictures of such a
> Bistigmat lens (this one for 9x12cm) here, which seems to
have the serial
> number 32914:
>
> http://fotoartmagazin.hu/oldtimer/bistigmat/
>
> It has no shutter, you have to expose with the lens hood
and this sort of
> "rotation aperture" (or whatever it is called in England)
did not fit very
> well with my impression of state of the art from the 30s.
>
> Tor
>
Well, I wish I had seen this before my last post:-)
It turns out that there are at least two lenses called the
Bistigmat. One was a lens of the convertible type, similar
to the Convertible Protar, but with a different arrangement
of the element powers, c.1890's. The other is this lens. I
can't read Hungarian either but can make out some stuff from
the text and illustration. This lens appears to be of the
Steinheil "Periskop" type. A symmetrical lens with two
meniscus elemenst, c.1865. These operate at f/15.
The stop of the lens illustrated is a rotating disc with
several stops on it. This type of stop was introduced in the
1860's but used for a long time after that. Iris diaphragm
stops were introduced in the 1880's so one would guess this
lens dates from not much later than that and probably
earlier.
The illustrated lens appears to have a two position
adjustment of some sort. Perhaps someone with better German
than mine (just a few words) could make out what the words
near the arrows next to the movable screw say.
--- Richard Knoppow Los Angeles, CA, USA dickburk@ix.netcom.com
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