Help identify a Goerz Dagor lens please

[HartleyFalbaum]

I have had this lens a long time, but just "found" it again. An unmounted f6.8 180mm (/250mm). Marking on front (?) element "CP Goerz Berlin No 48250 Dagor 1:6,8 180mm" and on the rear (?) element " Germany 250". The glass looks really good. The markings are on the outside diameter of they elements. Front outer diam 31.43mm, Thread is 29.43mm diam and 0.5mm pitch. Rear outer diam. 31.41mm, thread diam. 29.41mm, pitch 0.5mm.

Every picture of Dagor i've seen have the markings on the front, not the OD. The S/N is low for the numbers I see on this forum. Could this be from some other application?

I would like to take some pix with the lens,-I have a 5x4 Graphic View. I don't want to spend a fortune and find out the lens is not good for pictures. I assume a Copal #0 or a Compur #0 or some such would need to have adapters made--perhaps a #1 would be easier to adapt.

So I would appreciate enlightenment and advice.

Thanks in advance

[Dan Fromm]

I could be mistaken, suspect that the "250" engraved on the rear cell is the last three digits of the serial number.

When you say "unmounted" do you mean that you have a pair of cells with no barrel or shutter?

[IanG]

I think Dan's right, my Goerz-Ihagee 135mm Anastigmat (Dialyte) has the last 3 numbers of the SN on the rear cell. It's not very common for the markings to be on the outside of a front cell but it does happen where a manufacturer wants to ensure fitting in shutter without having to use the next size up, my CZJ 165mm f5.3 Tessar is marked on the outsside, I have quite a number of CZJ Tessars and it's the only one marked this way.

The lens cells would have been in a Dial set Compur or far more likely a Compound, but that SN if correct pre-dates Goerz using the DAgor name and the introduction of the Compound shutter.

If it's optically in good condition it's a good useable lens if you can find the right shutter, plenty of contrast and coverage.

Ian

[HartleyFalbaum]

Yes, it is a pair of cells--front and rear I assume. Thanks for the thought about the rear number. The engraving is clear and the S/N is correct, I'm pretty sure, so that is a mystery. Anyone out there have an idea about the proper spacing of the two cells?
Thanks

[IanG]

I posted ascan of an advert showing the different sizes of Dial set shutters on APUG (http://www.apug.org/forum/index.php?threads/dial-set-compur-shutters.138914/) tube lengths aren't given unfortunately. It may be that your cells fit an old style Compur #1, threads etc are different to the later rim-set Compurs.

It's still possible to find shutters, I've a pre WWII Ibsor (modern #1 size) never been used, blank aperture scale etc, and have found 3 similar Press Prontors. Probably your best bet is flea markets or camera fairs and an older camera with a dial-set shutter.

I have some lenses in Dial-set #1 Compurs so could measure the tube length if needed.

Ian

[HartleyFalbaum]

Thanks Ian;
Any guidance would be much appreciated. I can machine adapter if needed, but length of spacing is unknown. Trial and error would be time consuming if I can't find data.

[IanG]

It depends which shutter it should actually fit.

My Meyer WA is in a Dial-set Compur #1, barrel length is 23.0mm internal tube thread Diameter is 30mm, but it sounds like your Dagor is meant to be in a #0 Normal, tube length 18.65mm, tube thread Internal diameter 27mm, or the #0 W tube of 28mm diameter. I don't have a #0 W to measure but I think it's most likely this one Dagors are very small compact lenses.

The threads are very fine the difference between internal and external thread diameters is less tha 0.4mm which is why I think #0 W shutter.

Ian

[Dan Fromm]

Um, about trying random shutters to find out what fits. I recently visited Eric Beltrando (visit his site dioptrique.info) and we talked about what to do with dagor types. His ray-tracing program makes the point that dagor types' image quality is very sensitive to cell spacing.

[IanG]

I agree Dan, the best option is to find someone with Goerz (Berlin) 180mm Dagor in a shutter and get them to measure the barrel length. The other issue is the cells are mounted differently in some barrel mounted Dagors compared to those in shutters. That's comparing a 120mm Dagor in a barrel to mine in a Compound, quite different so that's also something to look at.

If the cells are from a shutter they won't fit the wrong sized Dial set Compur as the #0 Normal and #0 W have a different sized thread.

Ian.

[Luis-F-S]

You could just send him to SKG and let him figure out the spacing and mount them in a shutter. That's what I did with my 6 inch golden Dagor cells that didn't have a barrel. I'm sure he has dimensions on other Dagors he has mounted on file.