Very strange light leak on Mamiya RB67

kamvachon · Aug 9, 2025

Hey guys! I just developed some rolls at the lab and there is a very strong and consistent light leak across almost all the rolls: (http://imgur.com/a/7OYvorw)
The light leak is blue on the negative and comes out red on the scan. It starts strong at the beginning/end of the film and has a consistent line across the edge of the roll. Some shots it manifest more likes waves across the image.

I just checked my Mamiya RB67 and the light seals look pretty good as I changed them this year.

Any idea where it could come from on the camera so I can narrow down where to change the light seals? Thanks so much for the help!

koraks · Aug 9, 2025

Looks like a leak on the film magazine.

Rick A · Aug 9, 2025

I bought light seals for my RB 67 from these folks, inexpensive and easy to replace. They even have videos to guide you.

Mamiya Light Seals Archives

Mamiya Light Seals. USCamera has parts, installation guides, part lists, service manual downloads and more. We have a large stocking inventory of parts for Mamiya imaging products, film camera light seals and more. Contact us with any questions you may have.

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Donald Qualls · Aug 11, 2025

Thats at the lower side of the film magazine, when in default horizontal position. Presuming it's about the same density over the whole length of the roll, I'm going to guess it's not a light leak in the camera, but a processing issue (shows on the negs, so we can eliminate scanning problems). The starts and stops of film advance would produce variations in density if it were a light leak -- a couple minutes between frames would expose the film more than an immediate advance-and-shoot.

Looks to me like your lab owes you several rolls of film and a refund on the processing (they can't replace the images, but you might well save some of them by cropping).

reddesert · Aug 12, 2025

I believe that light leaks that show up orange/reddish on C-41 film (orange in the positive image) typically indicate the source of the light leak is hitting the back of the film. It shows up orange because it's filtered through the film base and dye layers. I fixed a camera once where the previous owner showed me an orange light leak and it turned out the back door hinge and latch seals were very degraded - but that was a 35mm camera.

I don't know the source of your leak, whether in the back or processing step. It would be a little harder to get a leak through the back of 120 film on an RB67, because of the backing paper, and the film path of the RB67 is mostly emulsion-side-out.

Donald Qualls · Aug 13, 2025

reddesert said:
It would be a little harder to get a leak through the back of 120 film on an RB67, because of the backing paper, and the film path of the RB67 is mostly emulsion-side-out.

I would mark this as well nigh impossible. As noted, the RB67 is emulsion out throughout the film path, and a backside leak would have to bypass the backing paper. It's possible to get an edge leak in a 6x9 red window film path, but once again, that will have huge variations in density as the film moves past the window and then stops for seconds, minutes, or up to weeks (if you leave cameras loaded like I do).

250swb · Aug 14, 2025

The OP says in some instances it looks like waves, additionally on the negative there seems to be a second leak over another leak, but the straight edge aspect to the leak are odd, but even so I think with the leak also catching the film edge a lot of the evidence makes it look a fat roll.

Donald Qualls · Aug 14, 2025

250swb said:
in some instances it looks like waves,

I missed that in the OP. Still -- fat roll on multiple rolls? Maybe the film back is missing the spring tab that keeps the film tight on the takeup spool?

Very strange light leak on Mamiya RB67

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