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Jim C.
7-Sep-2013, 13:23
As Charlie Brown once said - AAUGH !

I dropped the rear element of my lens, it was not a good sound, I expected to
see it in two pieces but there was only a scalloped chip in the lens, I actually found the chip
and was wondering if anyone attempted a repair using an optical cement ?

Andrew
7-Sep-2013, 13:53
haven't tried that, but I do have a lens where the chipped area was just painted black so it isn't spraying light around.

Jim C.
7-Sep-2013, 14:10
The chipped area extends a bit into the rear crown glass, actually looks like a mussel rather than a scallop.
I don't think painting it will do, unfortunately, but fortunately I don't seem to see anything
with 4x5, or even 8x10, I would like to try to repair it if possible.

101538

Vick Ko
7-Sep-2013, 16:49
Wow, can't hurt to try. Did you find the entire chip?

This was my standard optical cement http://www.optical-cement.com/cements/cements/uv.html#uv69

I saw some optically clear epoxy potting compound at an art store, and thought it might work too.

Good luck

Jim C.
7-Sep-2013, 18:22
Found the entire chip, Vic, I'll have to check your link, as well as what Edmund Optics has.

E. von Hoegh
9-Sep-2013, 06:51
You can glue the chip back on with UV curing optical cement, balsam, or other stuff. The issue is, the cement layer, however thin, still has a finite thickness which might and might not cause a problem. If it causes a problem, you still have the option of painting it black.

Jim Jones
9-Sep-2013, 08:40
I agree with E. von Hoegh. A bit of black tape that masks the area of the chip will let you test the idea of painting the damaged area. You may find the lens quite satisfactory, especially at smaller apertures.

Steven Tribe
10-Sep-2013, 02:05
Balsam is much easier to work with than synthetics.
As the shear is right up to the lens edge (otherwise it wouldn't be a shear!) you have to remove the glass from the brass mount.
Although you can only see one piece, there will be fine glass debris on both surfaces which will need removal. Use plenty of balsam as there be peaks and troughs in the fracture that can cause trapped air pockets if you are stingy.