Mirror lens

Hello,

I have a Konica Hexanon ARM 1000mm F8 mirror lens that need a repair. It looks as if a ring or shim was knocked loose near the front glass. Opening the front doesn't seem too hard, just need large spanner.





I never touched a mirror lens before so I was wondering if anyone knows of they all require collimation or any other special care.

Here is the homemade spanner I tried. The wood cracked before the lens retaining ring even budged. I'm not sure how to get the ring off at the moment.

It is possible that there is threadlocker on the retaining ring - you could try applying a little alcohol, or acetone if there is no plastic anywhere near it (acetone attacks many plastics) - and try again. With something this large you may need to fixture either the lens or the spanner - for ex, make the spanner out of a 2x4, clamp spanner to workbench, use both hands on the lens.

If you do get it apart, mirror lenses are basically the same thing as a Schmidt-Cassegrain or Maksutov-Cassegrain telescope used by many amateur astronomers, and there are resources in the amateur astronomy world for checking the collimation of such telescopes. The front glass is an aspherical corrector plate, and it has a secondary mirror on the back of it, in the center. I think that the centering of the secondary is pretty important, but the alignment of the corrector plate is less so.

Jarrett said:

Here is the homemade spanner I tried. The wood cracked before the lens retaining ring even budged. I'm not sure how to get the ring off at the moment.

View attachment 410917

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Build a stronger spanner.

Arthurwg said:

Build a stronger spanner.

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I would have to find someone to make it. I do have a way to machine tools. If I can find someone local I will.

SK Grimes would be a source for a stronger spanner. Not sure if their standard one is long enough, but they could make you one that is.

I will try and ask.

I took the lens to a camera repair shop and even they couldn't get it out.