Zeiss Jena Biotar iris transplant

[Lee Rust]

I recently acquired two Carl Zeiss Jena Biotar 58/2.0 lenses for very little money. One is M42 mount with a mangled iris diaphragm but clear glass, while the other is Exakta mount with a working iris but hazy, scratched-up glass with fungus. How practical might it be to transfer the Exacta-mount iris mechanism into the M42-mount barrel? The two lenses appear to be of similar early 1950s vintage, so if their internals are compatible, could a careful novice do the job or should it be left to a specialist?

My thanks for any advice or observations.

 

[Don_ih]

You would need to take both lenses apart to compare the individual aperture blades. They would need to be exactly the same, including the pins and slots. If they're off by even the tiniest amount, it won't work.

Aaaaaand .... putting together an aperture can be one of the most irritating things you ever do. The blades are flimsy and tend to want to slip apart as you reassemble the lens.

 

[ic-racer]

As above, the ‘broken’ blades might just need cleaning and reassembly.

 

[Dustin McAmera]

It's not something I would attempt myself. OTOH nobody ever learnt to do stuff without trying things they didn't know at the outset they could do.

There is this at Rick Oleson's site:
http://rick_oleson.tripod.com/index-81.html

 

[Lee Rust]

The aperture blades are badly bent, so likely beyond any effective straightening and re-installation. That Rick Oleson page is an excellent resource though, so I might well acquire some proper tools and give it a try. Both lenses are useless as they are, so there's no big loss if things don't work out.

Thank you, everybody.