65mm f/4.5 lens won't fit on RB67 Pro SD camera

Discussion in 'Medium Format Cameras and Accessories' started by B.S.Kumar, Aug 17, 2010.

  1. B.S.Kumar

    B.S.Kumar Subscriber

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    I've had a Mamiya RB67 Pro for some time now, along with 127mm and 65mm lenses. Recently, I bought an SD body. I can't figure out why the 65mm lens won't mount on the SD body. It works perfectly on the Pro, but it feels as if there's something obstructing the lens when I fit it on the SD. I've tried to fit it to the SD immediately after removing it from the Pro, to eliminate any errors on my part, but no go. When returned to the Pro body, it works fine, of course. AFAIK, it should work on both cameras. The 127mm works fine on both bodies. Both are non-C lenses.

    Any suggestions?

    Kumar
     
  2. fmajor

    fmajor Member

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    I really am not sure about these (i am new owner of a Pro-S), but could it be that there is an adapter that allows you to put the lens on the Pro and maybe needs to be removed to be fit to the Pro-SD? Or maybe there's an adapter in the Pro-SD that needs to be removed?
     
  3. Steve Smith

    Steve Smith Subscriber

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    The Pro SD (which I have) has a larger opening at the lens mount. Older lenses can be fitted with a collar to ensure good registration of the lens to the body. This will need to be taken off when putting the lens on an older body with a smaller diameter opening.

    http://www.adorama.com/MYRBLMAR.html


    Steve.
     
  4. B.S.Kumar

    B.S.Kumar Subscriber

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  5. MattKing

    MattKing Subscriber

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    My understanding has always been that the larger throat on the Pro SD results in a sloppy but otherwise fully functional connection between the camera and the older lenses. Use of the adapter takes out the "sloppy" factor, and helps protect against dust and moisture making its way into the body.

    Does the 65mm mount and function?

    FWIW, the mount on the 65mm pictured looks to be very worn (looking at the wear pattern at about 3:30 in the picture posted).
     
  6. B.S.Kumar

    B.S.Kumar Subscriber

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    Both are original lenses, prior to the C models. And the 65mm is used, but functions perfectly on the older Pro camera, with good results. But it won't mount on the SD, which is the reason for this thread...

    Kumar
     
  7. MattKing

    MattKing Subscriber

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    Hi Kumar:

    Both your camera bodies will likely have some wear in the lens mount, as will the lenses. If I understand these mounts correctly, they are designed to be usable and accurate even when somewhat worn or slightly damaged. If, however, the wear or damage gets to be too much, they will stop working.

    It may be that the wear points on the 65mm lens and the older RB are complementary, and therefore allow you to mount the lens on the older body. If the wear on the Pro SD lens mount is not complementary to the wear on the lens, it may not work.

    When I asked if the 65mm could be mounted on the Pro SD body I chose my words poorly - sorry about the confusion. I was trying to determine whether it was a situation where the lens appeared to function, despite what appeared to be a poor fit, or whether it was a situation where the lens could not be made to work on the camera at all.
     
  8. B.S.Kumar

    B.S.Kumar Subscriber

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    Matt, I understand. As you can see in the photo "65mm Lens on RB67 Pro SD", the lens will simply not mount on the SD. It feels as if there is something obstructing it. Can you figure out if there's anything wrong with the body or the lens from the other photos?

    Kumar
     
  9. MattKing

    MattKing Subscriber

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    Kumar:

    The only thing that I can see from the photos is the fairly extensive wear on the mount of the 65mm lens (at about 3:30 in the photo).

    EDIT: I've just noticed that it appears that the two lenses may not be cocked the same way (the pin adjacent to the green and red dots). As I'm sure you know, both the lens shutter and the body must be cocked when you try to mount the lens.

    Have you checked whether the depth of field lever is working properly on the 65mm lens. If not, it may be a sign that there is a problem with that part of the camera to lens connection.

    Hope that some of this might help.

    Does the stop
     
  10. B.S.Kumar

    B.S.Kumar Subscriber

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    The 65mm lens is fine - DOF lever, speed, aperture all work without a problem. I was playing with the shutter, hence the different positions of the cocking pins. Funny thing is, I mounted it on an extension tube, and then onto the SD body. It's not usable, of course, but works perfectly...

    Kumar
     
  11. Steve Smith

    Steve Smith Subscriber

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    Matt mentioned the cocking pin because both the body and lens must be cocked in order to remove and re-mount the lens.

    You probably already know that but it's worth pointing out anyway.


    Steve.