Meaning of the code on older Carl Zeiss lenses

[Ron (Netherlands)]

On my German cameras I use mostly the older Carl Zeiss (Tessar or Triotar) lenses in black mounts from the 20's 30's. These mostly had a tab for focusing or for changing the aperture. On this tab or on the rim of the lensmount there was usually a code composed of the letter A or B, a Roman numeral followed by a small Latin numeral, like e.g. BIV3 as this one:

182520

I have read somewhere that the Roman numeral stands for the inner diameter of the mounting ring - so the smaller lenses might have I, II and the larger ones have an VI or VII. Furthermore, my lenses with focusing mount bear the letter A, the ones without have the letter B. But what the little Arabic numbers like 2 or 3 mean is still a question for me ....

Here's another one with BIV2:

182521

Anyone who can provide more info on these codes?

[Steven Tribe]

Here is what Zeiss said about it.




The Roman/Arabic numbers are a size identification - like compur O,OO, etc. I don't think the specific match between numbers with lens type and focal length was published in catalogues.

[Dan Fromm]

1901 Zeiss London catalog: http://books.google.com/books?id=cnkWAAAAYAAJ&dq=zeiss+unar&source=gbs_navlinks_s

CZ London, really. In English. Click on the little starry wheel in the upper right corner of the screen to download as a PDF. P. 13 has a long list of numeric size codes, earlier pages explain the alphabetic codes.

Ron, this forum has resources. Here http://www.largeformatphotography.info/forum/showthread.php?138978-Where-to-look-for-information-on-LF-(mainly)-lenses is one that you should use.

[Ron (Netherlands)]

Here is what Zeiss said about it.




The Roman/Arabic numbers are a size identification - like compur O,OO, etc. I don't think the specific match between numbers with lens type and focal length was published in catalogues.

Thank you Steven, I have some of the older catalogues in pdf but none of them specifies this information....And indeed the Roman numbers match for instance with the numbers on older Distars and Proxars. But still the little Arabic numbers puzzles me.

[Ron (Netherlands)]

1901 Zeiss London catalog: http://books.google.com/books?id=cnkWAAAAYAAJ&dq=zeiss+unar&source=gbs_navlinks_s

CZ London, really. In English. Click on the little starry wheel in the upper right corner of the screen to download as a PDF. P. 13 has a long list of numeric size codes, earlier pages explain the alphabetic codes.

Ron, this forum has resources. Here http://www.largeformatphotography.info/forum/showthread.php?138978-Where-to-look-for-information-on-LF-(mainly)-lenses is one that you should use.

Thank you Dan, and yes I'm aware about these resources, very informative and a lot of catalogue info as well. However I wasn't able to find an answer to my specific question in those catalogues. Or do you mean I've should posted my question right there?

[Dan Fromm]

Ron, BIV3 decodes as special mount B ("objective mount fitted with iris diaphragm and fixed flange", without focusing helical), size IV subsize 3. All this except subsize 3 is in the 1901 Zeiss catalog I pointed you towards and the 1910 Zeiss catalog in the list. Subsize 3 is the mystery, everything else is clear.

The catalogs give the very strong impression that subsize indicates barrel length.

Sorry, you can't post to my list and anyway it has no forum attached. This is the place to ask, I'm glad you asked here.

[Ron (Netherlands)]

Ron, BIV3 decodes as special mount B ("objective mount fitted with iris diaphragm and fixed flange", without focusing helical), size IV subsize 3. All this except subsize 3 is in the 1901 Zeiss catalog I pointed you towards and the 1910 Zeiss catalog in the list. Subsize 3 is the mystery, everything else is clear.

The catalogs give the very strong impression that subsize indicates barrel length.

Sorry, you can't post to my list and anyway it has no forum attached. This is the place to ask, I'm glad you asked here.

Thanks so much Dan for clarifying; I wasn't aware it was possible to really look into the books you directed me to.
However I still don't seem to manage to open the 1901 catalog - guess the starry wheel procedure didn't work out well on my old mac.

[Dan Fromm]

About the starry wheel on the right. I just checked. When I clicked on it a window with four choices opened: My Library, Help, Advanced Book Search, Download PDF. Download PDF still works.

The 1910 catalog has the same information.

[Ron (Netherlands)]

Thanks again Dan. In my browsers (I checked with 3) I only get the first 3 options you mention. The Download PDF option is not mentioned.