180mm dagor

[schrochem]

As part of combined deal on Ebay I got a Doppel-Anastigmat C P Goerz Berlin Serie III No 2 F=180mm.
DRP No 74437 and the it's f6-f384
First question is what is f/6 on the stolze convert to for 'regular' f stop? I thought I had a diagram somewhere but can't find it.
Second question, the only other writing on the lense is toward the flange. It says No. 57. I'm assuming this is the serial no? If so, I thought those were typically large numbers. Does this mean it was the 57th lens (of this type) made?
Okay another question anyone know when it was made?
Thanks
Scott

 

[David A. Goldfarb]

57 might just be a production number used for keeping the two cells and possibly the barrel or shutter together. You might see if there's a 57 inside somewhere on the other cell.

 

[Ole]

Stolze 1 is f:3.16 (square root of 10).
So 2 is f:4.5
4 is f:6.3
8 is f:9
16 is f:12.5
And so on.

So Stolze 6 would be just about f:6.8, I guess...

 

[colrehogan]

Your serial number is the no. 74437.

 

[schrochem]

Thank you for the information. Diane, from what I've been able to find out, I believe the 74437 is the patent no. David, I looked and couldn't find anything on the inside. Thanks Ole for the info. I had found somewhere in the archives you had a similar lens. Does yours have a number near the flange?
Thanks again,
Scott

 

[Ole]

I can't remember Scott, but I'll have a look when I get home in a week or so.

There's a lot of things I'm going to have a look at - maybe I should just take a lot of pictures of everything???

 

[colrehogan]

I think I have a lens like this at home. I don't recall if it has Goerz Berlin on it, but it is a 7 inch Goerz Ser. III No. 2. I just got it back from having it put into a shutter.

 

[colrehogan]

Mine is a 7 in Goerz Dagor Ser. III No. 2. Sorry, no mention of Berlin on it. Mine is an f/6.8 at the widest aperture.