Mamiya RB67 ProSD - Lens wont attach correctly

Discussion in 'Medium Format Cameras and Accessories' started by izu, Mar 4, 2011.

  1. izu

    izu Member

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    Hi all, kinda new to these forums was well as to analog photography..

    I've got a RB67 Pro SD and a Mamiya Sekor C 3.8 90mm lens; my problem is that I can't manage to screw/mount the lens on to the body.. It aligns correctly but when I go to turn the "mounting ring" so to screw on the lens it only turns slightly and pretty much jams on to the camera and is even harder to take off.. I realise that if it is not fully attached it is unable to cock the lens fully.

    (The lens in the photo below is not cocked, I did cock the lens to the green dot before attempting to attach) Your help is much appreciated guys!

    Below is a photo of how much I can screw it on.. should go to from 12 o'clock to 3 but this is as far as I can move it.

    [​IMG]
    [​IMG]
     
  2. mickster

    mickster Member

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    The lens and body both need to be cocked before you can attach a lens.
    Cock the body using the cocking lever on the r-hand side of the body.
    Cock the lens by gently turning the two metal prongs on the back of the lens until they reach the red dots (see your last photo above).
    Now try to mount the lens on the body.
     
  3. izu

    izu Member

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    Thanks mickster but I've done both, cocked the body so that the mirror is down and the lens is cocked so that its reached the red and now rests on the green dot.. however I physically can not screw the ring all the way :sad:
     
  4. mickster

    mickster Member

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    In the last picture above the edge of the bayonet mount looks to be rather worn / bent: I'm talking about the silver coloured section of the mounting ring at about 12 o'clock in the last image. It could be that this is catching on part of the body mount: see if you can work out where this section is when the ring stops turning.
    If it is this piece then it might be possible to carefully file/bend the part so that it doesn't catch on the body mount.

    I'm assuming that you don't have access to another lens or body to confirm which is at fault?

    If gentle bending/filing doesn't do it then you'd need to get the lens repaired professionaly. At teh price these go for, it'd probably be much cheaper to just buy another lens in better shape.
     
  5. John Koehrer

    John Koehrer Subscriber

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    It's a pretty hard aluminum and I don't think it's going to bend gracefully. But, if you're careful and realize it may only need a tweak you should be fine. I'd think in terms of "if you see it move, it's too much" for measurement.
     
  6. izu

    izu Member

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    Thanks guys, Ill see what I can do.. purchased it off ebay, so I'm in contact with the seller hopefully we can work something out.
     
  7. keithwms

    keithwms Member

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    Hard to diagnose over the internet. Do you have another lens that does mount properly on this body?

    Looks to me like the lens was forced on or off at one point. In that case, it may need some repair. I am fairly certain it can be made to work again, I've seen lenses in much rougher shape.
     
  8. izu

    izu Member

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    I've only got the one body and the lens I purchased separately. Thanks for all the help, I was sure from the start that it was a fault with the lens mount. I've contacted the seller for a return, will have to keep looking :tongue:
     
  9. Rob. S.

    Rob. S. Member

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    I believe you need an adapter ring to mount pre-SD lenses on the SD. Sekor "C" lenses are pre-SD; the lenses introduced with the SD were labelled "K/L". These do need the same adapter, too, but they used to be shipped with one.

    Then again, I've read reports from someone who was able to attach his pre-SD lens without the adapter, but it seemed he needed to take real care to fit the right pins of the lens into the right holes on the body before tightening the lens.
     
  10. mickster

    mickster Member

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    This is not the problem the OP has. The 'adapter ring' is in practice simply a metal o-ring that fits around the end of the inner lens protrusion to give C lenses a snugger fit in the wider throat of the RB. In practice they're optional and I've been using C lenses on SD bodies without the rings for years with no ill effect. They don't affect the mounting/removal of the lenses which is the issue above.
     
  11. Paul Sorensen

    Paul Sorensen Member

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    Izu, many of us on APUG use these cameras, depending on where you are located, one of us would most likely be able to offer you the use of a lens to verify that it is indeed the lens that has the problem. I agree that this is most likely, but it seems that with the popularity of the RB67, it might be worth the effort to mount a different lens on the body and make sure that it works okay.
     
  12. Neil Grant

    Neil Grant Member

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    Judging by the reflections from the rear element, the lens is clearly a C. The scalloped mounting ring looks pre- C to me. Has anyone tried to repair the lens previously?
     
  13. paul ron

    paul ron Member

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    That jam ring may be turned in too far on the lens. Perhaps it was forced past the stop screw or replaced n not adjusted properly?

    Check to find the screw that stops the ring from turning too far? The screw is a set screw in the side of the ring at the bottom. Losen the screw and back the ring off the other way one turn, retighten the screw, all should be fine now.

    .
     
    Last edited by a moderator: Mar 9, 2011