I also have an earlier CPG Berlin Dagor, a 240mm #260383. I'm pretty sure this one was made after the lens was recalculated to use newly available types of glass, but maybe not. It behaves very much the same as the 30cm.
Inoticed the date on your drawings, 1926. This was very close to the date Zeiss acquired Goerz and formed Zeiss-Ikon in 1926.
Wonderful ! If you noticed , there are writings per lens , one with ink pen and newer one with the carbon pencil. I saw BAF at one of the later written pencil notes. BAF reminds me Barium Fluoride . Do you know when BAF invented , I invested to google but could not find.
If later lenses is fluoride based , they say they are very sensitive to atmosphere. I have 111mm f:1.5 Fluro Ektar and 10 pounds weight and what an amazing lens. I advise you to hold your lenses with hand and look to someone at night. If you see the detail , noise , plasticity , shadow , skin detail increase , curves are more visible , you would notice that your lens sees more than the eye.
E, you really should take a look at Eric Beltrando's site www.dioptrique.info. He has prescriptions for > 1,000 lenses, including some made by Goerz and Dagor clones from other makers, taken from patents and, in the case of Boyer lenses, Boyer's archives.
Eric wrote a ray-tracing program 030 that may still be available for download. He used it to evaluate lenses in a variety of ways, the results are posted with the prescriptions. Mustafa, you may find the spot diagrams illuminating.
I had been contacted with that gentleman years ago , but I had lost the address. Thank you reminding that one of the best site on web.
I want to ask , what does it mean that final negative coma analysis final result from one example lens. Does it mean there is still a error , or does it mean there is a excellence ?
I cant wait , I will open a thread. And how do we need to comment on spot diagrams ?
This is impressive site! I would not be surprised if LOMO guys are already looking in this site and searching what to resurrect next after success of Petzval project :).
Originally Posted by Dan Fromm