"Patrick Hamlyn" wrote in message
...
"R.H." wrote:

276 looks like a shutter (to an old camera? film equipment? I dont
know)

It's not a shutter, but it is part of a camera.

The shutter is behind the iris. The iris is first opened to the
calculated/selected F-stop, then the shutter opens briefly.

What we're looking at here is the iris.

Correct, except on this old camera part the shutter is in front of the iris.