Help to identify a cryptic light leak issue with a Pentax MX

Hello,

I'd like to ask for help diagnosing my recently acquired Pentax MX I started to test in preparation for a project. I've found some issues, nothing surprising, but somewhat baffled by the combination of them.

1, Initial.jpg: when I got the camera, I run 2 old, not very carefully stored roll of Pan400 through it and surprise, surprise, I got some light leaks (Type I, yellow). However, some of them were so solarised that I've put it down to an old roll.



2, Controlled.jpg: since I was also using new film now (Fomapan 400, bulk rolled by a redistributor), I did a speed/development/look test using this camera. What this image shows is that there is a frame gap issue (Type II, red), but I concluded it was not extreme and otherwise didn't detect leaks or perforation/advance-related issues, so I concluded I was good to go to an outdoor test. One note though, even though the objects in the frame have strong illumination, the ambient level was very low, relatively dark room during heavy rain, almost no window light.



3, Outdoors.jpg: Right after the controlled test, I've shot 5 rolls of Fomapan using the same technique and they all came back with issues that this contact sheet shows.
3,a: Light leaks (Type I, yellow): what's weird is that the leak is traveling through the length of the camera, it's not always in the same position relative to the gate! How is this possible, not sure.
3b: Frame gap issues (Type II, red)
3c: "Perforation shadow" (Type III, green). This can either be light-related or another thing is stress-induced exposure happening during film advance. I'd rule out development as the exact same technique on the previous roll was completely clean.



Any help in identifying the exact issue or ideas for what else is useful for testing to provide a repair technician with is welcome!

Thank you,
Andras

The fogging extending past the image area and along the sprocket lines is often caused by a light leak along the seams of the camera back. Degraded foam seals are often a plausible cause. The light leak would typically be in the area of the take-up spool. This explains also the printed-through sprocket holes.


This really just looks like parts of the windowframe you were shooting through/past. The vertical bar on the right coincides with a light leak. The same thing happens a few frames further on:

andrasikladi said:

a frame gap issue (Type II, red)

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On manual transport cameras, this is usually caused by not completing the transport cycle fully. You need to push the film transport lever all the way until it stops before you release it. If you release it prematurely, the film hasn't transported completely yet, but the shutter is already cocked for the next exposure. This results in a very narrow gap between the frames. A common cause in my experience is my thumb slipping from the lever as I transport the film.

All considered I think the main and probably only problem with this camera is a light leak on the film back.

Also, welcome to Photrio! I'd love to hear more about the project you're working on. Hopefully we'll get to see some photos when the time comes!

koraks said:

The fogging extending past the image area and along the sprocket lines is often caused by a light leak along the seams of the camera back. Degraded foam seals are often a plausible cause. The light leak would typically be in the area of the take-up spool. This explains also the printed-through sprocket holes.

View attachment 409432
This really just looks like parts of the windowframe you were shooting through/past. The vertical bar on the right coincides with a light leak. The same thing happens a few frames further on:
View attachment 409433



On manual transport cameras, this is usually caused by not completing the transport cycle fully. You need to push the film transport lever all the way until it stops before you release it. If you release it prematurely, the film hasn't transported completely yet, but the shutter is already cocked for the next exposure. This results in a very narrow gap between the frames. A common cause in my experience is my thumb slipping from the lever as I transport the film.

All considered I think the main and probably only problem with this camera is a light leak on the film back.

Also, welcome to Photrio! I'd love to hear more about the project you're working on. Hopefully we'll get to see some photos when the time comes!

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Thank you for the welcome!

What's surprising about the light leaks is that they usually seem to have a similar width, and they go all the way through the film, which would suggest the door hinge/or lock side. But why would they look the same regardless of the camera/Sun direction, including portrait mode? How would they travel around relative to the gate, yet remain parallel?

About the film transport: indeed, that happened one or two times. Occasionally, I also feel like something was slipping inside, but since I'm new to the MX and otherwise the transport feels quite smooth, I wasn't sure if this was to be expected. And once there was a "weightless click" sound, but the shutter didn't fire. Sounds like what you've described, maybe partially triggered by my action and most likely some worn-out gearing inside.

The project will take years to materialise, but you can find my (analogue and mostly digital) work over on my website.

andrasikladi said:

But why would they look the same regardless of the camera/Sun direction, including portrait mode? How would they travel around relative to the gate, yet remain parallel?

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The gate is unrelated to this leak. It's light that seeps into the camera body along a seam in the back and exposes the film directly on the take-up spool. This happens some distance away from the film gate. The exposed-through sprockets are the giveaway that the leak is happening around the take-up spool.

andrasikladi said:

my (analogue and mostly digital) work over on my website.

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Magnificent!! Thanks for sharing that; I think you're work is really beautiful, and especially because it extends much deeper than the superficial prettiness (which it certainly also has).

koraks said:

The gate is unrelated to this leak. It's light that seeps into the camera body along a seam in the back and exposes the film directly on the take-up spool. This happens some distance away from the film gate. The exposed-through sprockets are the giveaway that the leak is happening around the take-up spool.

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The reason I've mentioned the gate is not as a source of the issue itself, but it relates the exposed film to the camera. So, when I align the gate with the frame, I expect the leak to occur in a certain, recurring position. Or multiple positions. Not random, sometimes on the left, sometimes on the right. I think your mention of the sprocket holes is the solution: maybe it happens during winding? Anyways, will have to redo the sealing. The transport mechanism issue is more concerning.

koraks said:

Magnificent!! Thanks for sharing that; I think you're work is really beautiful, and especially because it extends much deeper than the superficial prettiness (which it certainly also has).

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Thank you!

andrasikladi said:

So, when I align the gate with the frame, I expect the leak to occur in a certain, recurring position.

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OK, I see what you mean.

What you're overlooking in your otherwise fine logic is that the fogging penetrates the wound-up roll of film on the take-up spool. So you'll see some variation in the distance between the same fogging band. Effectively, you should see a light band somewhere near the start of the roll, then darker bands at slightly increasing distances. This is assuming there's one single fogging event. On a typical roll shot in outdoor conditions, you get a repeated fogging as the camera is handled and several sees intense light hitting its back, so the pattern is usually less clear.

Long story short, your approach of matching the gate with the frame and finding the fogging spot/seam will work, but only for the site(s) one the film that received the direct exposure. Other bands will be on the layers of film underneath and the gate-match method won't work for them; there'll be a variable offset.

andrasikladi said:

The transport mechanism issue is more concerning.

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I don't see evidence of a transport mechanism issue. I'd start by shooting a roll and very carefully checking that you complete the transport cycle. If the problem persists on that roll, look deeper into it. But I bet it's gone if you transport correctly.

I would check the light seal at the door side of the taking spool first.

I had a very similar issue some years ago with a Ricoh Kr10x. The root cause was the light sealing of the rewind pin at the bottom of the camera, which felt apart. This let light into the bottom of the camera and from there it went to the film chamber via the sprocket axis mechanism.

koraks said:

OK, I see what you mean.

What you're overlooking in your otherwise fine logic is that the fogging penetrates the wound-up roll of film on the take-up spool. So you'll see some variation in the distance between the same fogging band. Effectively, you should see a light band somewhere near the start of the roll, then darker bands at slightly increasing distances. This is assuming there's one single fogging event. On a typical roll shot in outdoor conditions, you get a repeated fogging as the camera is handled and several sees intense light hitting its back, so the pattern is usually less clear.

Long story short, your approach of matching the gate with the frame and finding the fogging spot/seam will work, but only for the site(s) one the film that received the direct exposure. Other bands will be on the layers of film underneath and the gate-match method won't work for them; there'll be a variable offset.

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Makes sense, thank you for leading me through with this deduction!

koraks said:

I don't see evidence of a transport mechanism issue. I'd start by shooting a roll and very carefully checking that you complete the transport cycle. If the problem persists on that roll, look deeper into it. But I bet it's gone if you transport correctly.

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Hopefully, it's my fault. Only used a couple of Leicas and a Bessa for a few years, never had this issue - not easy to get used to the feeling that I cannot trust the most basic operation of the camera

Sanug said:

I would check the light seal at the door side of the taking spool first.

View attachment 409475

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Thank you for the picture, mine looks much thinner. I'll give it a shot.

Animalcito said:

I had a very similar issue some years ago with a Ricoh Kr10x. The root cause was the light sealing of the rewind pin at the bottom of the camera, which felt apart. This let light into the bottom of the camera and from there it went to the film chamber via the sprocket axis mechanism.

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Thanks, I'll keep it in mind, although I don't think there is a seal there in the MX but certainly close enough to the suspected location of the problem.