Pentax M42 adapter help needed

Discussion in 'Adapted Lenses' started by toobacat, May 21, 2012.

  1. toobacat

    toobacat Mu-43 Regular

    59
    Mar 21, 2012
    I just picked up this Pentax camera and lens at an estate sale this weekend and I want to adapt the lens to micro four-thirds. I was about to order a M42 to micro four-thirds adapter when I read that some of these lenses need an adapter with a flange. I'm not sure what what this means. Can someone help?


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    <a href="http://www.flickr.com/photos/22023930@N07/7244583502/" title="_1140086 by toobacat, on Flickr"> 7244583502_a5890a454e_b. "816" height="1024" alt="_1140086"></a>
     
  2. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    Feb 8, 2011
    Pacific Northwest, USA
    Keith
    I would assume that this is what is meant by an adapter with a flange. Fotodiox makes two versions of the M42 to :43: adapter, one with the "aperture shoulder" and one without. I'm not sure which M42 lenses require (or benefit from) the aperture shoulder.

    Other options for M42 adapters include those that offer tilt functionality and a line from Hawk Factory (on eBay) that offer focusing helicoids which can (as far as I can tell) function sort of like an adjustable extension tube.

    BTW, nice find. That Takumar 1.4 is a desirable lens.
     
  3. stratokaster

    stratokaster Mu-43 All-Pro

    Jan 4, 2011
    Kyiv, Ukraine
    Pavel
    Every M42 lens with an aperture stop-down pin need "aperture shoulder", otherwise the aperture will stay wide-open. By the way, all Super-Taks and SMC Taks have stop-down pins.
     
  4. Monza76

    Monza76 Mu-43 Regular

    98
    Mar 22, 2012
    Check to see if the lens has a manual/auto aperture control lever on the lens itself, if it does it will work with any adapter.
     
    • Like Like x 1
  5. toobacat

    toobacat Mu-43 Regular

    59
    Mar 21, 2012
    Thanks guys, now I understand. :smile: Monza76, it appears to have a manual/auto aperture control lever, but I didn't realize what it was until now. You can see the lever in the second picture. I has an "A" on one side and an"M" on the other.
     
  6. Grinch

    Grinch Mu-43 Top Veteran

    813
    Jan 9, 2011
    Canada
    Nice find, this is one of my favorite lenses.
     
  7. geoffox23

    geoffox23 Mu-43 Rookie

    20
    Feb 5, 2010
    Brisbane. Australia
    In photo 2, your lens looks to have a short extension tube fitted at the rear, against the body.

    You should unscrew it to have the lens focus correctly on your m43 adapter.
     
  8. Laurentiu Cristofor

    Laurentiu Cristofor Mu-43 Veteran

    200
    Mar 9, 2012
    Just so you know: this is one of the few radioactive Takumar lenses (the other one I know of is the 55/1.8, which is less radioactive apparently).
     
  9. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    Feb 8, 2011
    Pacific Northwest, USA
    Keith
    So is there any reason one would want to buy an adapter without the "aperture shoulder"? Does the shoulder hamper the function of some lenses?

    [​IMG]
     
  10. kinlau

    kinlau Mu-43 Top Veteran

    836
    Feb 29, 2012
    Some m42 lenses bump up against the flange. Most of my lenses fit just fine, but a few odd lenses have trouble, they don't completely screw in, so you have trouble with infinity focus.
     
  11. chicks

    chicks Mu-43 Top Veteran

    876
    Feb 1, 2012
    The Big Valley, CA
    The "shoulder" is removable on the adapter - three set screws around the outside hold the threaded ring in, the "shoulder" is just a washer below it.
     
  12. toobacat

    toobacat Mu-43 Regular

    59
    Mar 21, 2012
    I've never used extension tubes and didn't know what it was, but I removed it.


    I had never heard this before, hopefully it's not a hazard.
     
  13. DeeJayK

    DeeJayK Mu-43 Hall of Famer

    Feb 8, 2011
    Pacific Northwest, USA
    Keith

    I personally wouldn't be too concerned about the radiation, but others differ on this point. You may notice that the lens exhibits a yellowish color tinge, which is apparently a side effect of the radiation. This can be minimized with UV treatment (i.e. exposing the lens to sunlight). This post has an example of the yellowing as well as some discussion of the radiation.
     
  14. Ned

    Ned Mu-43 Legend

    Jul 18, 2010
    Alberta, Canada
    The radioactive lenses are cool. If you use them long enough (granted, it takes about 12 or 13 years of regular use), your eye turns to glass and it's just like looking through a camera lens all the time.
     
  15. toobacat

    toobacat Mu-43 Regular

    59
    Mar 21, 2012
    This one definitely has the yellowish tint, I just checked it today.
     
  16. geoffox23

    geoffox23 Mu-43 Rookie

    20
    Feb 5, 2010
    Brisbane. Australia
     
  17. Laurentiu Cristofor

    Laurentiu Cristofor Mu-43 Veteran

    200
    Mar 9, 2012
    Opinions are divided. Some sources say that because the elements decay, radioactivity actually gets worse in time (now being that bad time). Another source of concern is that they may emit gamma radiation (alpha and beta are less worrisome). If you search youtube, you should be able to find videos of them setting Geiger counters. This larger list of radioactive lenses is also interesting - the Takumar is used as reference :)
     
  18. Laurentiu Cristofor

    Laurentiu Cristofor Mu-43 Veteran

    200
    Mar 9, 2012
    I have that shoulder on an adapter and it doesn't even press the aperture pin fully - it is half pressed, which is as good as nothing.

    You definitely don't need this shoulder for the Takumar and for most M42 lenses. For those for which it might be helpful, you could also find alternative solutions to keep the aperture pin pressed. Finally, given the low cost of the third party adapters, you can always get another one later if you really think this feature would help.

    What I would be more concerned about is the ability to focus to infinity when using lenses wide open. I tried 3 different lenses with my adapter and none could reach infinity focus. I have the same problem with an LTM adapter.
     
  19. ryansinibaldi

    ryansinibaldi Mu-43 Regular

    161
    Mar 9, 2012
    I've read somewhere that some lenses will emit enough radiation equivalent to an x-ray over a period of an hour (assuming you have the lens in your pocket or something).
     
  20. toobacat

    toobacat Mu-43 Regular

    59
    Mar 21, 2012
    Roger Hicks wrote an article in Shutterbug Magazine in 1997 called "Hot Glass". There are some excerpts from it here. I haven't been able to locate the original article, but from what I read of it, it does appear that the radioactivity can get worse over time. The article says that the risk are small from the lenses, but it does warn against keeping a box of them under your bed. :smile: