I have purchased a 19 inch F7.7 Goerz Dagor in Compound shutter (appears to be the original, marked CP Goerz New York) to use on a 12X20 camera. In general, there should be no problem with coverage from what I understand. My question: the lens I have (serial # 754457, does this provide pretty accurate dating info?) is single-coated, both according to Lens and Repro, who sold it to me, and my own casual inspection. The front diameter looks just a bit smaller than the other, older, uncoated versions of the lens I have seen. Does coverage remain the same (eg adequate for 12X20 w/ movements)in the later vintage, coated incarnations of these lenses? What might be the date range on this lens?

Thanks for any help you can offer,

Nathan

-- nathan congdon (ncongdon@jhmi.edu), August 01, 2001

Answers

Nathan,

According to the Goerz serial number list I have (I think it's probably also somwhere on Tuan's site), this lens would date from the early 1930s. So, if it is coated, the coatings are not factory original and were added at a later date. Are you sure it's coated and not just displaying some oxidation ("bloom")? I'm not saying it isn't coated - just not original. I believe Goerz (like most others) began coating their lenses shortly after the conclusion WWII - somewhere around serial number 770xxx. That said, there were a few companies back in the 1940s and 1950s that offered retrocoating on older uncoated lenses. Given that the 19" Dagor was an expensive lens most likely owned by a professional photographer at that time, it is conceivable that the owner would have gone to the expense of having it retrocoated.

Not exactly sure on the coverage of your particular sample, but I had on older, uncoated barrel mount 19" f7.7 Dagor (~1910 vintage) that covered 12x20 with a little room to spare at f22. At f45, the usable image circle was three feet in diameter. This would be enough to cover 20x24 with movements. I think you'll be OK on 12x20.

Kerry

-- Kerry Thalmann (largeformat@thalmann.com), August 01, 2001.

Thanks, Kerry. I saw that listing of serial #s on Tuan's site after posting. It would certainly suggest the lens had been retrocoated. Guess I won't know for sure about the coverage until I mount it on the 12X20, which will be whenever Ron Wisner finishes the camera (at least I know the Dagor will still be around then, even if I'm not!)

Nathan

-- nathan congdon (ncongdon@jhmi.edu), August 01, 2001.

Nathan,

Did you ask Ron Wisner? He knows Dagor well and might have an opinion. Cheers,

-- Geoffrey Chen (DB45TEK@AOL.COM), August 02, 2001.