Leica 9cm f4 M mount lens advice?

[lushd]

I have just got a new old lens (see pic). It appears to be in great shape but when mounted on my M6 it won't focus properly. Aimed at a far distant object and fully rotated the rangefinder images won't match up. With closer objects they will, but something 10 feet away reads 50 feet on the scale (!). Any ideas for adjustments required?

Thanks all

 

[ZorkiKat]

I have just got a new old lens (see pic). It appears to be in great shape but when mounted on my M6 it won't focus properly. Aimed at a far distant object and fully rotated the rangefinder images won't match up. With closer objects they will, but something 10 feet away reads 50 feet on the scale (!). Any ideas for adjustments required?

Thanks all

Sounds like a previous botched repair job. The helicals sounds like they were not put back together correctly- it's easy to do this with a multi-entry threaded helical like the one used on the Elmar. See Thomas Tomosy's Leica Repair book (or search the 'net for similar reference sites?) for an explanation of how this works. You'd likely see what's going wrong...if you're good with tinkering, you might even be able to fix it 🙂

Jay

 

[lushd]

Well done ZorkiKat - the bit of advice about multi-entry threads made a lot of sense so after some swearing and a lot of fiddling it is now reading to within 1 ft of my trusted Elmar lens with the RF patch merging properly. I'm off shooting tomorrow. Many thanks!