Super Takumar 28mm f3.5 Broken M - A Switch

Discussion in 'Classic Manual Cameras' started by nateseff, Sep 11, 2019.

  1. Hi guys,

    So being the frantic person I am, I forced the A and M switch on my Super Takumar 28mm f3.5 lens (otherwise in immaculate condition) and now it doesn’t stay locked in A when off a camera body.

    It works as it should on my Spotmatic, whether in M or A (aperture closes when shot). My question is this - what exactly did I break in the lens mechanism that prevents it from switching when not on a body? Is it worth taking apart to fix? I’m wondering if it’s a piece of metal that I bent or if it’s a plastic tab (if so, would it affect anything or should I remove it?)

    Any insight would be appreciated.

    Thank you
  2. I haven'T any idea what material or how it'S broken..and here'S the kicker ..if at all!! If it'S not broke....

    I am a frantic person too.... and simply knowing it'S not 100% drives me crazy...but you are likely to have a bigger problem trying to figure out what'S wrong rather than accepting the situation. It works on the camera...where it needs to work!! IT'S NOT BROKEN. Bring this behind me Satan!
    nateseff likes this.
  3. m42dave

    m42dave Dave E.

    Here is a disassembly guide for the SMC Takumar 35.3.5, which should be similar to your lens (the SMC lenses do have the extra little pin on the mount which keeps the A/M switch in the "A" position on the Spotmatic F, ES, and ES II).

    Takumar Super Multi Coated 35/3.5 disassembly
    nateseff likes this.
  4. The switch can't really be "forced", unless the internal aperture mechanism has first become ceased or half ceased causing excessive resistance when manipulating the switch. Normally it switches from "A" to "M" with moderate resistance, but that's how it's meant to be. There will be indent "locks" at each extremity, and it's possibly the indent locking part has broken or something has slipped out of place. As well as the indents, the mechanism provides a lock in "M" mode.

    In "M" mode, the chrome pin gets locked in position for manual operation. In "A" mode, the pin is at the other extremity and is free to move radially for the camera to automatically move it to the designated aperture setting when the shutter fires.

    Off the camera, the pin should be locked in "M" mode (aperture settings done by hand). In "A" mode, the pin should move freely and if you move the pin by hand you should get movement of the aperture blades

    It will be no different when the lens is on the camera. When set on "M", you use the aperture ring. When set on "A", the camera will move the pin.

    Are you sure you've checked the lens properly ? It sounds like it's working fine and you've just mistaken the "A" setting as a "locked pin" setting when in actual fact the pin is supposed to move radially about a 1/4"
    nateseff likes this.
  5. m42dave

    m42dave Dave E.

    Just to clarify my previous comment, the "extra little pin" on the Super-Multi-Coated/SMC Takumars is not the stop-down pin. When mounted off-camera (or on the F/ES/ES II), the A/M switch will be locked in the "A" position; if you press this pin in (as it would be when mounted on an older Spotmatic or other M42 camera) then you can move the A/M switch.

    There are also a few Super-Takumars with this extra pin as well, though they are uncommon.

  6. Driving right now but will get back to this - all good mentions (need to read more closely) BUT I should mention it was in A when I received it and it wouldn’t budge. NOW I realize I should’ve pushed the pin down or have attached it to a lens to switch it but I forced it to M and now it switches back and forth no problem AND still works as it should both on and off the camera, all except for it locking on A when off the camera. It’s a super multi coated Takumar
  7. m42dave

    m42dave Dave E.

    Then it should like my lens above. It's possible that the little extra pin I show is stuck (pressed in) or damaged. If the pin won't free up, and you forced the A/M switch, then you may need to remove the mount and see if the interlock is broken or can be re-adjusted. However, if the diaphragm otherwise works as it should, then the switch interlock feature really isn't needed if you aren't using one of the later Spotmatics.

    And please be careful while driving. :)
    Last edited: Sep 11, 2019
  8. Haha noted! And everything still works, all apertures etc. the ONLY thing it won’t do is lock off camera in A anymore. I’m just hoping it isn’t a piece that can get lodged somewhere in the lens and cause a huge issue.
  9. Drives me 10000% crazy as well aha hoping it’s not broken. Thankfully it’s a lens I could somewhat easily replace down the line but optically it’s very clean and cosmetically it doesn’t have any scratches or dings so I don’t wanna have to go searching again for one as good as this one.
  10. Thank you this is a great reference to have...unfortunately it doesn’t go into detail with th switch mechanism but definitely good to have in case I do need to open it up
  11. This might apply to an older Takumar lens, I'm looking at it right now and as m42dave has posted it does have that little extra pin. That being said, when I move the switch off camera, it does go in and out (ever so slightly). So is it even broken? How come the switch wouldn't work off camera at first without forcing it if it still works after? Maybe it was jammed/stuck? But if that's the case then that goes against everything I know about the M - A switch on m42 lenses. Thinking maybe the pin's bent or something (if that's what it is inside) and then I suppose I won't need to open it up to take any broken pieces out. I just checked all apertures as well using B on Auto mode and everything works as it should. On manual mode everything opens and closes as it should both on and off the camera.
  12. m42dave

    m42dave Dave E.

    As I noted above, the SMC Takumars are designed to do this (i.e., switch locked in "A" position when off camera, or mounted on the F/ES/ES II bodies). This is normal operation for these lenses, which were designed for open-aperture metering with these particular cameras.

    That tiny extra pin should spring back if you press it with your fingernail or tip of a pencil. When it's pressed in, then you should be able to slide the A/M switch back and forth freely; when released, the A/M switch will lock in the "A" position again. If it doesn't, then either the pin is stuck or something is broken inside.
    Last edited: Sep 11, 2019
    nateseff likes this.
  13. It's probably stuck/broken in the pressed in position. I guess I'll have to let it be then, I definitely don't want to have to open it up if the piece can just sit 'freely' inside of the lens without issue.

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