"Marco Milazzo" wrote in message
...
Hard to tell without seeing the whole piece, but #276 looks like a
universal lens mount for studio cameras. This was a device to mo9unt
any diameter lens. The iris was closed by turning a small knob on the
side.

I put a few photos of the whole piece on the site below, I think it's just
the front part of an old camera:

http://pzphotosan52.blogspot.com/