Mamiya RB67 light leak - lens?

Discussion in 'Medium Format' started by jon_lawrence|1, Dec 4, 2017.

  1. Hi all,

    I recently shot a few long exposures using a Mamiya RB67 with both a 90mm and 50mm lens. The images shot with the 90mm were fine but the 4 I shot with the 50mm have what appears to be a light leak? I'm hoping it's just a case of the lens not being properly attached to the body (I shot with the 90 first and switched to the 50). It occurs in exactly the same place on each neg, regardless of camera position (see attached image). Has anyone else had this happen to them before? I'm hoping it's more a case of my carelessness than a busted lens.

    Any input would be greatly appreciated.

    Jon

    Pub-1.jpg
     
  2. Assuming we're talking about the curved lines at 10 and 2 o'clock, I suspect internal reflections within the lens structure due to the bright lights in the field of view. (But I don't own a Mamiya, so perhaps another reader will have a better idea.)
     
  3. paul ron

    paul ron NYC

    i see the circular marks. it does look more like a reflection, not a light leak. in fact if you orient the image as it would be in the camera, it looks like the bottom of the filter ring is reflecting since you are shooting into the light source.

    try shooting another roll during the day and avoid looking into the light source.
     
  4. I'm a bit skeptical of this being the actual problem, but it's worth mentioning that if you are using a Pro-SD body there is a metal O-ring that fits to the base of all lenses except the 500mm and SHOULD be in place when a lens is mounted on the body.

    K/L lenses came with this ring, while it needs to be fitted to earlier lenses.

    I've personally not seen any serious side effects from not using the ring, but if I did see them i suspect they'd look something like that.
     
  5. Very strange!
    The inner 'flares' (if that's what they are) show some concentric rings. Could they be a reflection of the inside of a lenshood? Or of camera baffling?

    They're also similar to "Newton's rings" - interference rings from closely-spaced reflective surfaces.

    I suggest you examine the lens closely for cement separation between elements. This'll show up as silvery-looking patches in the lens.

    Apart from that, I have no idea how those rings could be produced.
     
  6. Hi Jon, Its very common on any lens' with the angel of view that you are using.....and its all todo with lens flare, just use the lens again and raise it up about 12+ inches.:)
     
  7. "Its very common on any lens' with the angel of view that you are using...."

    - Flares are indeed very common. What are uncommon are the concentric bands within the flare arcs. Look more closely!
     
  8. paul ron

    paul ron NYC

    im sure those lines are the filter ring reflecting back into the camera.

    turn the image upside down (oriented how it is in the film mag) and see how the lights are reflecting up into the camera.
     
  9. Agree with the ideas that the marks are either flare or filter ring imaging. Doesn’t look like like leaks or lens malfunction to me. How was the floating element set?
     

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