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Will M39 mount lens focus to infinity on Nikon?
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PostPosted: Mon Oct 24, 2011 3:55 am    Post subject: Will M39 mount lens focus to infinity on Nikon? Reply with quote

There are many M39 mount lenses out there I'd like to pick up cheap to play around with. I know M42 will not have infinity focus on Nikon unless you get the adapter with the optic and that degrades IQ. But can you have infinity with no optic in adapter with M39 lens?


PostPosted: Mon Oct 24, 2011 3:59 am    Post subject: Reply with quote

They are worse than m42.

M39 (Leica) Screwmount Focal plane distance : 28.80 mm

I use this chart to help me :

http://en.wikipedia.org/wiki/Flange_focal_distance

Anything under "Nikon" should fit with an adapter. Thats how I use it with my Canon t2i.

You can search on ebay for ["Whatever mount" Nikon]... you'll see if at least China make some.


PostPosted: Mon Oct 24, 2011 10:40 am    Post subject: Reply with quote

No, only for macro, not for infinity (if you talk about the M39lenses made for Leica).

BUT one important exception are M39 enlarger lenses (M39 Leica thread mount is THE enlarger standard mount), which from a certain focal length onwards are able to focus to infinity (from about 80mm onwards; with some mechanical tricks from about 50-60mm, depending on lens an its back focal distance) using a focusing helicoid (and some lens/camera adaption rings).





It is shown here on my BLOG: http://photographyoftheinvisibleworld.blogspot.com/2011/01/how-to-determine-length-of-focusing.html

and here a tricky "sunken" mounted razor sharp 3.5/63mm EL-Nikkor :


PostPosted: Mon Oct 24, 2011 11:31 am    Post subject: Reply with quote

There's also the Zenit M39 lenses. But these have the same register distance as M42, so while better than LTM39, you still won't get infinity focus.


PostPosted: Mon Oct 24, 2011 11:33 am    Post subject: Reply with quote

Screwmount rangefinder lenses are designated LTM39, not M39, because they do not conform to the true metric standard. The thread is 39mm OD, but the pitch is a non-standard 26 tpi. On true M39 lenses, as used on the early Zenit SLRs, the thread pitch is 1mm. They are not interchangeable, not just because of the different register distances, but because the thread will bind after a couple of turns.

The Soviet lenses for early Zenit SLRs have a true M39 x 1mm thread, and you can use a simple double-threaded ring adapter to mount them on M42 cameras or adapters. However the register distance is virtually the same as M42, so using them on a Nikon has the same problems.

Bill, many M42 and M39 lenses can be adjusted to achieve infinity focus on a Nikon. Often it's a very simple job - just remove the name-ring round the front element and slacken 3 or 4 screws. If you want to try this with a cheap lens, I've done it with a Pentacon MC 1.8/50.


PostPosted: Mon Oct 24, 2011 1:35 pm    Post subject: Reply with quote

Fully correct Peter, LTM or Leica Thread Mount is M39 x 26tpi (26 threads per inch or 25.4mm, so the difference is small but significant). Quite often M39 is used for LTM a bit sloppy (as I did), as M39 x 1.0 is very rare to find (but exist).