Quote Originally Posted by bernard_L View Post
You did not tell us did you intend to do with it?
Suggestion:
Glue the two pieces together. I would do it with UV-curing glue (need sunny day); do not use instant glue. Before you expose to sun, make sure they are precisely aligned, using the match of the crack surface and checking the surfaces and edges match.
Then:
- Either use as-is; at least do a first test
- Or, if you think you see objectionable flare, cover the region of the (glued) crack with a thin line of black paint. All you will suffer is a small loss of effecitve aperture (plus diffraction by the edges of the black region, but this should be negligible wrt te native geometrical aberrations).
When you finally re-mount the lens, use some foam or other between the ring and the glass; three small pieces in a triangle should be OK. Whatever method you use, make sure you preserve the centering as per the original design.
I intended to use it on the camera I'm currently building.
I might give that a go, but would prefer not to glue anything just yet... having said that, I can't make it any worse really.
Tomorrow I'll rig something up to see how bad it effects the performance.