Diagnosing a Mamiya RB67

dearcomposer · Jul 4, 2024

Hi y'all, I recently purchased a Mamiya RB67 Pro-S and just ran a test roll through the camera. Some of the exposures have this dark stripe at the top of the frame, both when in portrait and landscape. This leads me to believe it's not a development issue, but potentially a lens or sensor issue. Maybe a pressure plate issue? I've never seen this on another of my other camera, 35mm or 120mm. I was hoping maybe someone has seen this and can point me into the right direction of repairing it.

It didn't happen on every frame, but on most frames.

Lens: Sekor-C 127mm f/3.8
Stock: Portra 400
Dev: Arista C-41
Scan: Epson V600 (this an issue in some of the photos with the scanner backlight bleeding too, not worried about this today)

Alan Edward Klein · Jul 4, 2024

Try scanning without the film holder. Place 3 or 4 shot section on the glass where the scan takes place so you can see the whole thing including the black borders. Select the film on the prescan. Then it should be easier to see the problem.

dearcomposer · Jul 4, 2024

Alan Edward Klein said:
Try scanning without the film holder. Place 3 or 4 shot section on the glass where the scan takes place so you can see the whole thing including the black borders. Select the film on the prescan. Then it should be easier to see the problem.

I can see, just holding the film up to the light that this dark soapy line is on the negative itself. Put perhaps I'll do another scan to see if I can learn anymore

MattKing · Jul 4, 2024

There is some sort of obstruction near the bottom of the light path.
Scans won't help as much as a digital photo of the negatives the negatives themselves - backlit, and showing the film rebate, frame numbers and spave between the frames.
It is likely that the obstruction is moderately close to the film plane, but not at the film plane.

dearcomposer · Jul 4, 2024

Here are the updated scans. I also realize that the light spot is also on the negatives so I might be dealing with a light leak.

MattKing said:
There is some sort of obstruction near the bottom of the light path.
Scans won't help as much as a digital photo of the negatives the negatives themselves - backlit, and showing the film rebate, frame numbers and spave between the frames.
It is likely that the obstruction is moderately close to the film plane, but not at the film plane.

I will open up the body and see what I can find.

MattKing · Jul 4, 2024

We don't want to see scans - pictures of the negatives please - particularly the space between the frames.

koraks · Jul 4, 2024

This is a development artefact cause by insufficient developer volume, or a film reel that was not slid entirely down onto the center column. Essentially, part of the film spent a considerable part of the development time not submerged in the developer.

This is either a light leak hitting the front of the film, possibly caused while the film was in the camera. Alternatively, it could be a spot of retained silver due to incomplete fixing and/or bleaching, but a light leak seems more likely. You could try running the affected negatives through bleach and fix again and see if that helps. If so, you know where to look.

dearcomposer · Jul 4, 2024

MattKing said:
We don't want to see scans - pictures of the negatives please - particularly the space between the frames.

Here's 7/10 of the negatives. I skipped a few that were blank.

koraks said:
View attachment 373449
This is a development artefact cause by insufficient developer volume, or a film reel that was not slid entirely down onto the center column. Essentially, part of the film spent a considerable part of the development time not submerged in the developer.

View attachment 373452
This is either a light leak hitting the front of the film, possibly caused while the film was in the camera. Alternatively, it could be a spot of retained silver due to incomplete fixing and/or bleaching, but a light leak seems more likely. You could try running the affected negatives through bleach and fix again and see if that helps. If so, you know where to look.

A development issue sounds very likely. I'm still learning and have had some waivering success with my color chemicals. I just had never seen it before like this. After diving into the body, I've noticed a lot of soiled light seals, as well as some loose connections between the back adapter and the body.

koraks · Jul 4, 2024

For the development, it's clear that it's a coverage issue. What tank are you using?
For the light spots, I'm still on the fence. Might be a light leak due to degraded seals, but incomplete fixing also still seems like a possibility. I'd re-fix those negatives and see if it makes any difference.

Also, welcome to Photrio! I hope we'll be able to help you iron out the kinks so you can enjoy your medium format color photography!

dearcomposer · Jul 4, 2024

I’m using a standard Patterson 3-reel tank. I’ve developed maybe 14-15 rolls on it and never had this problem so likely user error here. I’ll definitely re-bleach & fix to see if it’s a camera issue or if I need to get fresh chemicals.

And thank you for the welcome! I’m so thankful there’s a community like this that I can learn from!

Don_ih · Jul 4, 2024

The light leak could be from the bellows. You can check that easily enough if you take the back off, trip the shutter so the mirror goes up, then shine a flashlight in there in a dark room and see if any light is visible around the bellows (you look at the outside).

It does look a bit like the film may have been touching itself during fixing - there's something about that that looks like unfixed film.

MattKing · Jul 5, 2024

After seeing the negatives, I agree with koraks about it being due to low developer volume.

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