Related Links:
http://www.docteroptics.com/
Since questions about Docter Optic lenses come up in this group from time
to time,
I prepared a table of their LF lens data from my Docter Optic general
brochure
and the individual leaflets for each lens (from 1994), and to
add some additional
informations on the company. I hope this is helpful. If readers of
the newsgroup
have additional information, especially on the weight of the shuttered
versions and
the smallest f-stops, please e-mail me and I will add it to the table
and repost it.
Arne Croell
After the unification of Germany the (formerly West-German) Docter
Optic group bought
some of the plants of the former Carl Zeiss Jena combine, including
the one in Saalfeld
(Thuringia), founded 1911, which made the Zeiss Jena large format
optics in the GDR
and (at least some) before WWII. All the Docter LF lenses, except the
Doctar WA, were originally
designed by and for Carl Zeiss Jena, and used older ones are of course
marked that way. If there
is any difference between the Docter Optic lenses and the last GDR-made
ones it is probably
the coating. Note that the first years after Docter Optic acquired
the plant (1991), the Tessars
were sold as Docter-Optic Tessars, later the name was changed to Doctar.
Around 1995 or 1996 Bernhard Docter, the founder of Docter Optic, died
and the group
went bankrupt.The main parts of the group were eventually sold to a
holding owned by
Rodenstock, Hella, and Bosch(the latter two being German car part manufacturers-Docters
original core business was car headlight optics). Apparently Docter
does no longer manufacture view
camera optics, but they still make other ones like CCD camera and projection
lenses.
They have a website at:
http://www.docteroptics.com/
1997 they had an offer for their remaining large format lenses on this
web site (removed in early 1998),
mainly for wholesale. Thus some new lenses may show up on the market
the next years (from some
posts I learned that Badger Graphics in the US and a UK company named
Mr. Cad had some),
but after that they are only available used.
Remarks:
The 65mm Doctar WA is a new development and was introduced in 1993-1994;
it is a
Biogon/Super-Angulon-type wide angle.
Tessars were first sold as Docter-Optic Tessars, later the name was changed to Doctar.
The (non-W) Apo-Germinars are of the "Dialyte" or "Celor" type, similar
to Apo-Artars or Apo-Ronars.
Around 1994/1995, Docter Optic introduced an improvement of the Apo-Germinar,
a version
with an additional removable brass ring spacer ("Trimmring" in german)
between the front cell
and the shutter. It is intended to optimize the performance at the
edges of the field at magnifications
smaller than 1:5 (up to infinity) by changing the cell spacing. For
magnifications between 5:1 and
1:5 the ring is ommitted, for all other magnifications it is used.
There was a report in the magazine
"PhotoTechniqueInternational" about the performance at infinity, at
least in the German edition
(PhotoTechnikInternational 5 (Sept./Okt.)1995, p32-33).
The image circle for the Tessars/Doctars is at infinity. The Apo-Germinar
and Apo-Germinar-W
series are process lenses and the image circle is given for 1:1. Their
image circle at infinity is
approximately half that value. Note that Docter Optic did not specify
for which aperture the image
circles and coverage angles are valid; it is probably f/22.
According to Docter Optics, best overall performance ("Arbeitsblende"=working
aperture) is
at f/22 for all lenses except the three Apo-Germinar-W's, where it
is atf/16.
Except for the Doctar WA, all lenses were offered both in barrel and
in Copal shutters. At least
the larger ones were originally designed (in the GDR) for use with
a shutter behind the lens
(a "Grundner" type shutter, somewhat similar to a Packard shutter),
and not for No.3 shutters.
Thus the long focal length have two different maximum apertures, depending
on the mount.
Note that sizes, weight, and _filter threads_ are often different for
barrel and Copal versions!
Although they are not useable for large format, I included the 50mm
and 75mm Tessars,
because all Tessars were listed as a group in the original brochure.
For the 600, 750, and 1000mm Apo-Germinars I only have a drawing of
the setup which does not
allow to decide whether the outer two lenses of each cell are cemented,
or just close together
with a small airspace (as they are in the similar long focal length
Apo-Ronars with 6 lenses).
* means there was either contradictory information (general brochure
vs.
individual leaflet) and I chose the one more reasonable (to me), or there
were obvious typos that I
corrected.
? denotes missing information.
+ after the smallest aperture means that it can be stopped down further,
but there are no markings.
Disclaimer: In addition to errors I might have missed, I may also have
introduced new ones, so
please use this table only for preliminary information and countercheck
any important informations,
e.g. before deciding on a purchase. My personal experience is limited
to a 300mm Apo-Germinar
(which is a nice little lens in my personal opinion).
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