Can you identify this lens design from 30's?

BurstMox · Expire: 2016-08-02

Hello,

I came across a soviet prototype from 30's with an interesting lens design.

It's a 270mm/4.5 lens that cover a rather large format (6x6 and more). I disassembled it (elements are just screwed, you only need fingers), optical design looks quite simple. I'm rather sure the frontal and last glass is not a doublet, but I can make mistake. All the elements are well spaced. The schema is not super accurate, I made it myself, but these are the right type of glass (plano-convex, positiv meniscus, etc...). The size is also relatively on scale.

#1

At first I thought about Ernostar, but shape of the elements do not really match.

Any idea of western lens that had this optical schema in 30's or earlier?

Thanks!

stevemark · Joined: 29 Apr 2011 Posts: 3908 Location: Switzerland

While I'm by no means an optical expert, the lens to me looks like a very simple telephoto construction. The front pair must be positive, and probably is a simple color corrected doublet, the middle element seems to be planparallel, and the rear is negative for sure. Alas - a typical, very simple tele lens ... But others may know more.

I'm a bit puzzled by the strong concave-convex curvature of the rear lens, though. Unusual for simple tele lenses ... but maybe acting as some sort of field flattener if the image angle was/is rather large for a tele lens?? I mean it could be a "normal lens" using "tele cosntruction" ...

S

BurstMox · Expire: 2016-08-02