Re: Lens Details Was large format...etc

From: Richard Knoppow ^lt;>
Date: 11/26/05-03:43:42 AM Z
Message-id: <010f01c5f26d$e81192b0$b6f75142@VALUED20606295>

----- Original Message -----
From: "davidhatton" <>
To: <>
Sent: Saturday, November 26, 2005 1:12 AM
Subject: Lens Details Was large format...etc

> Wayne,
> I got an email from SNIP telling me that things were all
> ok now but when I tried again I got bounced. C'est la viz.
> Thanks for the advice. I got the lenses out today so here
> are the
> details on the lens rim/shutter
> 1: C.P. Goerz AM. OPT. CO. then a gold dot (looks like a
> brass insert -
> not paint anyway) , DAGOR 12 in F: 6.8 No. 813768. There
> is also a
> narrow gold band around the front of the barrel. Rear
> element : 813768
> Shutter Ilex No 4 Universal. F6.8 to 64, speeds
> 1,2,5,10,25,50,100,B,T.
> Glass is greeeat and shutter works fine.
> 2.C.P. Goerz AM. OPT. CO.,W.A. DAGOR 6 1/2 in F:8 No.
> 777485.Rear
> element : 777485. Shutter Ilex Acme synchro No.3. Glass
> greeeat shutter
> works fine.
> 3.C.P. Goerz AM. OPT. CO. APOCHROMAT (then a red dot)
> ARTAR 19 in. F.11
> NO. 795101. Rear Element 795101. Again great glass.
> Shutter is busted so call it in barrel.
> Camera is beautiful and little used, all black with brass
> fittings, ground glass protector in f64 backpack. I also
> have 12 double film holders. All with little use. All
> purchased by me personally in the USA when I lived in CT.
> Now I am in Turkey and conditions are a little different
> to Westport :) hence the sale.
> Let me know what you think.
> Much obliged, and apologies to all for this blatant
> commercial intrusion.
> Happy holidays
> David H

  Well, you are in Turkey and I have turkey in me.
  The Gold Dot Dagor was the last of the line. I don't know
if the design was changed from the original Series III
Dagors but manufacturing precision was improved. The Gold
Dot has an excellent reputation. The serial number is well
beyond my list which does not go beyond 791,500, about 1955.
The Gold Dot Dagor shows up in catalogues around the mid
1970s and a version of it was made by Kern after Schneider
bought out Goerz American Optical in the late 1970s. The
Dagor has maximum coverage of around 87 degrees when stopped
down to f/45. A single element can be used alone, preferably
behind the stop, with a focal length of about 1.8 times the
combined focal length and about f/13. Because the single
cells are not corrected for coma they must be stopped down
to at least f/36, coverage is around 45 degrees.
  There was an earlier version called the Golden Dagor,
identifiable by the polished brass front cell. AFAIK, this
was just a sales gimmick for the standard Dagor. They are
still very good lenses but should not be confused with the
Gold Dot series. Gold Dot Dagors are coated.

The f/8 Wide Angle Dagor was made only by Goerz in the
United States. The German version made by Goerz in Berlin
and after the 1926 merger by Zeiss was f/9. Performance of
the two is probably not much different. By making the
maximum aperture smaller the coverage can be extended to 100
degrees at f/45. 77,845 dates from the early 1950's. These
are probably not coated, Goerz American was one of the last
lens makers to routinely coat lenses.

   The Red Dot Apochromatic Artar was also the last of the
series except for those built by Schneider after buying
Goerz. The Apochromatic Artar was the most widely used
process lens for photoengraving. The Red Dot series is
coated and the element spacing is adjusted for various
conjugates depending on the mounting, focal length, and
what was ordered. Older Apo Artars are all completely
symmetrical and optimum at 1:1, the Red Dots were optimised
for anywhere from 1:1 to around 1:10. Those with long
congugates were usually shutter mounted.
  Actually the Apo Artar has corrections which are pretty
stable with changes in object distance. The main aberration
which is picked up is coma and that can be eliminated at
infinity focus by stopping down a little. Apo Artars of any
age are extrememly sharp. Those made before the Red Dot
series are uncoated and have a little flare due to the 8
glass-air surfaces. When used for their original purpose of
half-tone photo-engraving the flare makes no difference
since it can be compensated for by slight changes in
exposure. I have a very old (1920's) Apo Artar which does
not seem excessively flary. 19 inches is the most common
focal length for process lenses.
   The main limitation of the Apochromatic Artar is its
limited coverage, around 45 degrees in the catalogues
although it will just about cover an image circle of
diameter equal to its focal length. This is typical of the
generic type known as a Dialyte. The serial number is
probably around 1960. The first of the Red Dots came out in
1953 but the serial number I have for it is not correct
because I have one with a slightly lower Snr.

  What kind of shutter is it in and what exactly is broken?
  Steve Grimes used to be a magician with Ilex shutters but
I don't know if the people who run his shop now will
undertake the more difficult jobs he gloried in.

  If this was meant to be a private e-mail you hit the wrong

Richard Knoppow
Los Angeles, CA, USA
Received on Sat Nov 26 03:44:26 2005

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