Mamiya RB67 problem

Discussion in 'Medium Format' started by tom_kondrat, Jan 12, 2021.

  1. I noticed there is a problem with some of the pictures taken with Mamiya RB67 + 65mm f4.5 lens. You can see a brighter spot of light almost in the middle of the image (it almost looks like a smoke). This happens only in situations when the subject is quite dark but the background is very bright (please see attached photographs).
    I went to the camera repair shop. They said it's not caused by a light leak. It's usually the problem with the lens (some mold) but they checked it and it had no problems.
    I've read that when using UV filters (mine is not very expensive) there can be some flares occuring on the images. Could that be the problem?
    Has anyone ever experienced something similar? Could you kindly help me to solve this issue? Thank you very much!

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  2. Flare is usually more distinct than this, which is more subtle. But the effect does seem to move around a little from photo to photo, so it could be low-level flare interaction from a cheaply coated UV filter. To be sure, you would need to shoot a test roll, using the same subjects shot twice (with and without the filter). Do you use the matching lens hood/shade for the 65mm? That can help sometimes, tho medium format wide lenshoods can be tricky.

    When I had the RB system some years ago, I did get minor fungus in two different 65mm older "C" lenses, but it was at the edge of front element and did not produce this effect.
     
  3. I would guess it’s a problem with the filter. First make sure both the lens front and back elements are clean and the filter also. Then shoot several images similar to the above first with the filter in place and again with it removed. Are you using a lens hood? That’s a bit of a wide angle for the RB.

    Rick H.
     
  4. I’ve just noticed that the floating element was set to 1m but the focus was set close to infinity when taking the pictures. could that have created this issue by any chance?
    or is there a problem with the lens design? (the lens is clean, I checked again)
     
  5. If the floating element setting is way off from the focused distance, it could create an overall unsharpness effect, but probably not this lighter patch issue (which is very subtle in your samples).

    The 65mm C lens is generally considered a decent wide for medium format, but there is some sample to sample variation depending on the year it was made, so some of them are mediocre. Do you have any other lenses you can compare with (standard, portrait)? You really need to verify you're only having a problem with this one lens. If the same "lighter patch" issue occurs with other lenses, the camera body, film back, or your technique are causing it. If the issue disappears with another lens, this particular 65 won't work for you and you should consider replacing it. If its your favorite focal length, consider upgrading to the newer K/L 65mm which has top notch quality control and uniformly excellent performance (sharpness, contrast, flare).
     
  6. An internal reflection (in the body or lens)? The sky is in the same spot for all the pictures, can you see it with no sky in the picture? Camera up-side-down (Sky at bottom)?
     
  7. It was the lend problem. I bought 65mm f4 K/L and it's all good now.
     
  8. What is a "lend" problem?
     

  9. Misspelling of lens?
     
  10. What was the lens problem?
     
  11. Maybe it means it was lent to him :) . Peter
     

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