Petzval Locking Ring

[rguinter]

Greetings:

I recently purchased a Petzval lens in a magic lantern mount. Glass is very nice but the assembly was missing the threaded locking ring.

Anyone know a source whre I might find a ring of the correct size and thread?

I've long since lost my contacts for machine shop services.

Thanks in advance for any suggestions. Cheers. Bob G.

[Steven Tribe]

Whilst about 1/2 of all old camera lenses have lost their flanges, it is even worse for ex lantern lenses. Perhaps 95%?

There are two types. The rack and pinion - and the more humble "pressure fit" type. If you have the most common type of projection petzval, which are approximately 2" in diameter, it may be worth your while taking off the existing mount/adjustment device and make an alternative with a couple of (or 3!) mounting tabs (soldered or screwed) to a new brass/copper tube which would function as a new "pressure fit" mounting/focussing outer tube. This would not be practical with a really heavy Petzval. Excessive play between the two tubes can be "taken up" with suitable material (felt, velvet). Does this make sense? I can construct some illustrations tomorrow if necessary.

Finding a suitable flange will be a lost cause and getting a universal iris mount an expensive experiment.

[Richard Rankin]

If you can find a flange/mount with the proper internal diameter, you can slide in the tube and use blue tack or silly putty or anything like that to hold the tube in position, and just screw down the flange onto the lens board. Ugly but works quite well and is a cheap solution.

I didn't keep the diameter of that lens, so PM me and I'll check my spare flanges for a suitable one when I get home this weekend if you want to try the 'cheap' way to mount it.

Cheers,Richard

[rguinter]

The thread major-diameter is 2.225" (56.5 mm). I didn't measure the pitch. Tube diameter is 53.0 mm.

While working at a major electronics research center at one time, finding a lock-nut to fit would have been little problem. The machinists collected spare parts for just about everything and lock-nuts came in all sizes.

Now I'm thinking of having one made to fit if necessary. This magic lantern assembly is in such nice shape that I would hate to damage it with a jerry-rigged mount. Bob G.

[Richard Rankin]

I've got three near that but only have a plastic ruler so can't really do 56.5mm. One is a cast iron monster that came off a magic lantern and measures awfully close (to me) so it might do the trick but is heavy and ugly and would need holes. Another is like a threaded metal lens board and the last is a brass one. Let me know if you want me to pop them in the mail to you to try. Cheers, Richard

www.richardrankin.com/sale/DSC_0022.JPG