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Question on M39 Lens Mounting

Discussion in 'Adapted Lenses' started by godwinaustin, Aug 9, 2013.

  1. godwinaustin

    godwinaustin New to TalkEmount

    6
    Aug 9, 2013
    Hi everyone. I am wondering if there is any difference in mounting an M39 lens via a M39 to M42 step updater and then to a fotodiox M42-Nex adapter VS buying a new M39-Nex adapter and skipping the step up ring.

    Any functional/performance difference between these two methods?
     
  2. addieleman

    addieleman Passionate amateur

    Nov 13, 2012
    Netherlands
    Ad Dieleman
    The M39 adapter is much shorter than the M42 adapter, allowing your M39 lenses to focus to infinity. The M42 adapter with an M39 step-down ring would not allow infinity focus, not even close, the M39 lens would be much too far from the sensor.
     
  3. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Well, it's a bit more complicated than that. M39 mount is both a rangefinder mount with a registration distance of 28.8mm and a slr ( Zenit ) mount with a registration distance of 45.2mm. M42 has a registration distance of 45.46mm.

    So, assuming you have a slr lens then stepping from M39 to M42 and from M42 to NEX you will be fine (assuming proper maching tolerances). Ad is spot-on for rangefinder lenses. It would be one way to get much closer focus with a rangefinder lens, but as Ad said you'd lose infinity focus.

    Searching ebay for M39 lenses I have to wonder how many people have bought slr lenses thinking they were getting rangefinder lenses.
     
  4. godwinaustin

    godwinaustin New to TalkEmount

    6
    Aug 9, 2013
    very helpful, and as I was suspecting. Ordering the m39 adapter then, thanks so much.:)
     
  5. godwinaustin

    godwinaustin New to TalkEmount

    6
    Aug 9, 2013
    the lens i am referring to is a m39 helios 44-2
     
  6. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Hmmm… according to Camerapedia the 44-2 is already M42 mount, but them wily Russians did some strange stuff with lens mounts. ;)

    Either way it's a slr lens and you'd go the M39/M42/NEX or M42/NEX to use this lens on your NEX.
     
  7. godwinaustin

    godwinaustin New to TalkEmount

    6
    Aug 9, 2013
    and Bimjo, if I understand you correctly the helios would have a registration distance (which I need to google since I have no idea what that is.) of 45.2, which would work correctly with the m39-m42 adapter mounted to the m42-nex adapter.

    is there an issue then in using this m39 helios at 45.2 on an m39 mount with a registration distance of 28.8? Is the lens then too CLOSE to the sensor?
     
  8. godwinaustin

    godwinaustin New to TalkEmount

    6
    Aug 9, 2013
    the very early versions of this lens were an M39 mount
     
  9. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    As I said, it can be complicated. ;)
     
  10. godwinaustin

    godwinaustin New to TalkEmount

    6
    Aug 9, 2013
    Thanks again. Got my pentax slr stolen recently, and just moved to this NEX system because of an excellent deal on an Nex-F3. With the focus peaking this is such a rad system with older lenses, already using Pentax primes on it. Wonderful.

    Thanks again, and thanks for a very informative welcome to the forum!