Quote:
Originally Posted by Stefan Buda
Today I unscrewed the two retaining rings and all the internals came out as one stack, comprising of three lens groups and two cylindrical spacers. The lens in the middle is much smaller than the other two, so it has a ring around it to bring it up to the same diameter as all the other internals.
Interestingly, they used three pieces of sticky tape to hold the small lens in place, on the concave side, and the spacer on that side has a chamfer that contacts the edge of the lens - or more exactly the pieces of sticky tape. Maybe the sticky tape is meant to act like a cushion to protect the lens. In any case the edges of the lenses seem to be hand chamfered and not very even. The internals are a rather loose fit into the bore of the housing. I measured the parallelism of the two spacers and found the long one to be out by 0.2mm and the short one by 0.4mm - no comment. Also the ends of both spacers, where they make contact with the large lenses, are very rough, almost as if they were cut with a hacksaw. Is it a cushioning layer that has been painted on?
I'm reluctant to measure the wedge error of the lenses as there is a dander of scratching them. It may be possible to re-mount them in a self centring manner if the wedge errors are not too bad.
Next I turned another fixture so that I can hold the housing from the other end and see if the outside features were turned in one setup. Unfortunately I could not get it to run true. Probably the end is out of square and makes everything wobble when screwed into the fixture.
That was the autopsy. Any suggestions for the resurrection?
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This is what I suspected all along and I wished it was not true. I suspected early on that the threads were not square due to the changing shapes of stars when the adapter was rotated to another position. With any luck you can find a solution to the problem.