Diagnosing light leaks on 35mm (Leica M3, Jobo Tank)

Ian Leake · Jan 27, 2022

Can you help me with these light leaks? I think there are more than one...

The attached image is an iPhone photo of the start of a roll of film that I developed yesterday. The first frame has been ruined, and the subsequent frames have issues around the sprocket holes and the top edge.

The film is FP4+ exposed in a Leica M3 and developed in a Jobo 1530+1510 tank. The reel was at the bottom of the tank. I load the reels and the tank in my darkroom, then switch on the lights for processing.

If you look closely at the top edge, you can see a thin line of fogging that varies in thickness. I get this on every roll, but it's never enough to give problems when printing so I have ignored it (for a while I taped-up the bottom of the camera but this made no difference so I stopped doing it). Always these lines are only there for the first 8-12 frames then go away; on this film they're gone by frame 14.

The sprocket holes show some sort of shadows, mostly on the bottom but also a few on the top. They are also only at the start of the roll of film, and gone by frame 14. I've not seen these before on other rolls.

The problem at the start of the roll only affects the first frame. I've not seen it before on other rolls.

Do you know what could be causing these? Something in the camera? Mishandling when loading or unloading the film? Something wrong with the tank when developing? I'm grateful for any help you can offer! Thanks in advance.

Rudeofus · Jan 27, 2022

The dark patterns at the extreme edges are caused by your film roll kept in place by the plastic spindle. Developer gets trapped while stop bath and wash water didn't get through, and together with fixer the developer turns into a fog machine. Since the spindle doesn't reach into the image area, these patterns are of no concern.

Then there is the fog in the image area on frame 0A. Are you 100% sure, that the film was would up fully on the spindle when it was in the tank? It does look like one end of your film was not properly spooled up and touched the previous winding, thereby causing the exact same thing I described with the outer edges above.

Ian Leake · Jan 27, 2022

Rudeofus said:
The dark patterns at the extreme edges are caused by your film roll kept in place by the plastic spindle. Developer gets trapped while stop bath and wash water didn't get through, and together with fixer the developer turns into a fog machine. Since the spindle doesn't reach into the image area, these patterns are of no concern.

That makes a lot of sense, thank you.

Rudeofus said:
Then there is the fog in the image area on frame 0A. Are you 100% sure, that the film was would up fully on the spindle when it was in the tank? It does look like one end of your film was not properly spooled up and touched the previous winding, thereby causing the exact same thing I described with the outer edges above.

I'm as sure as I can be. Being the first frame it would have been right in the centre of the reel, and everything felt right when I loaded the reel.

bdial · Jan 27, 2022

You may want to check the right-hand strap lug. Mine popped completely off one day, the mounting hole goes into the film chamber (leastwise it does on an M4-2).

Ian Leake · Jan 27, 2022

bdial said:
You may want to check the right-hand strap lug. Mine popped completely off one day, the mounting hole goes into the film chamber (leastwise it does on an M4-2).

Thanks. I'll try taping this up when I've unloaded the current film. However, if there's a light leak here, wouldn't it show on the whole roll not just the first frame?

ic-racer · Jan 27, 2022

Rudeofus said:
The dark patterns at the extreme edges are caused by your film roll kept in place by the plastic spindle. Developer gets trapped while stop bath and wash water didn't get through, and together with fixer the developer turns into a fog machine. Since the spindle doesn't reach into the image area, these patterns are of no concern..

No.
Leaking cassette.

Light Capture · Jan 27, 2022

There are quite few possibilities here.
Some observations:
- There is a black line on top edge of the film. It's on the bottom of the camera. Not uncommon but it would mean there could be something in that area. Since you taped it already I'm not sure if it could be around the flap cover with ISO indicator on the back side. If it doesn't appear on other films than it's probably something specific to FP4. It can also be from Jobo reel.
- That doesn't appear to be bulk loaded cassette. It shouldn't be related to leaky cassette since you say you had similar leak on previous films.
- There are some dark spots around sprockets that look similar to dark "light leak" looking areas on the start of the roll.
- Leica cameras have shutter cloth rollers on both sides. That means there is larger distance between the cassette, area where film is exposed and take-up spool. This depends on how you load the roll in the camera. Some people start winding with back open to see if film moves. Cassette chamber on Leica is well shielded and if bottom plate is kept partially open just to allow back ISO flap to be closed that could cause partial leaks on start of the roll.
- It could still be uneven development. This area is the closest to the core and could be buckled preventing flow of chemistry. Also depends if it's developed in Jobo processor or by hand.

The way I would troubleshoot this issue is to eliminate either camera or processing first.
Either to develop in different tank with different reels. If rotary process is used that could explain why it happens on first 8-12 frames.
F (film) setting is too slow and actually causes uneven development. Linear speed through fluid is much lover for frames closer to the core. When speed is increased everything works well.
It's detailed well in updated Jobo user manuals.
If it looks the same with different processing method, camera would be next to look at and there could be some other issues.
Since it doesn't happen after 8-12 frames, I would guess that camera should be fine.

Other method I use is to look at film itself and evaluate the actual defects. This will help compare all defects and see if they have the same cause from the start of the roll to the place where it stops. Film defects when scanned don't tell the whole story. Different issues can look the same in the scan. When actually looking at film and defects, discolorations, fogginess and areas that were not fixed can be identified. This will separate if there are unrelated issues. Dark areas around sprockets are most likely not the light leaks but processing issues due to film sitting in reels.

MattKing · Jan 27, 2022

ic-racer said:
No.
Leaking cassette.

I agree.

Ian Leake · Jan 27, 2022

Light Capture said:
There are quite few possibilities here.
Some observations:
- There is a black line on top edge of the film. It's on the bottom of the camera. Not uncommon but it would mean there could be something in that area. Since you taped it already I'm not sure if it could be around the flap cover with ISO indicator on the back side. If it doesn't appear on other films than it's probably something specific to FP4. It can also be from Jobo reel.
- That doesn't appear to be bulk loaded cassette. It shouldn't be related to leaky cassette since you say you had similar leak on previous films.
- There are some dark spots around sprockets that look similar to dark "light leak" looking areas on the start of the roll.
- Leica cameras have shutter cloth rollers on both sides. That means there is larger distance between the cassette, area where film is exposed and take-up spool. This depends on how you load the roll in the camera. Some people start winding with back open to see if film moves. Cassette chamber on Leica is well shielded and if bottom plate is kept partially open just to allow back ISO flap to be closed that could cause partial leaks on start of the roll.
- It could still be uneven development. This area is the closest to the core and could be buckled preventing flow of chemistry. Also depends if it's developed in Jobo processor or by hand.

The way I would troubleshoot this issue is to eliminate either camera or processing first.
Either to develop in different tank with different reels. If rotary process is used that could explain why it happens on first 8-12 frames.
F (film) setting is too slow and actually causes uneven development. Linear speed through fluid is much lover for frames closer to the core. When speed is increased everything works well.
It's detailed well in updated Jobo user manuals.
If it looks the same with different processing method, camera would be next to look at and there could be some other issues.
Since it doesn't happen after 8-12 frames, I would guess that camera should be fine.

Other method I use is to look at film itself and evaluate the actual defects. This will help compare all defects and see if they have the same cause from the start of the roll to the place where it stops. Film defects when scanned don't tell the whole story. Different issues can look the same in the scan. When actually looking at film and defects, discolorations, fogginess and areas that were not fixed can be identified. This will separate if there are unrelated issues. Dark areas around sprockets are most likely not the light leaks but processing issues due to film sitting in reels.

Thanks, you've given me plenty of things to follow up with. It's also really helpful that you've said why you think these may be reasons. I was using rotary development, and one easy change is to go back to inversion. I may also add a reel of expired, unexposed film next time to eliminate any camera-related issues. I only have one working 35mm camera so I have nothing to compare with.

Light Capture · Jan 27, 2022

Ian Leake said:
Thanks, you've given me plenty of things to follow up with. It's also really helpful that you've said why you think these may be reasons. I was using rotary development, and one easy change is to go back to inversion. I may also add a reel of expired, unexposed film next time to eliminate any camera-related issues. I only have one working 35mm camera so I have nothing to compare with.

One more thing to add. I usually sacrifice a roll for tests like this and use 5-10 frames remove and develop. You could also add piece of unexposed strip and use it as a control strip as comparison. Could also try loading developed film to reels and see if it can be pushed in such a way that it buckles film close to the core. Some reels can simply have imperfection and cause issues.
If you have darkroom changing bag, you can place camera, tank and scissors inside, load it with film and get front of lens only to stick through one sleeve. Than few test shots can be fired and film can be removed and processed. That should eliminate any camera leaks.

Ian Leake · Jul 20, 2022

I thought I'd update this thread with my final conclusions, just in case anyone finds this thread via search. Several people got it right. Thanks!

The mess at the start of the roll:

I'm certain this was a problem with the cannisters. I switched to self loads with Kodak snap caps, and the problem immediately disappeared. Later I used a roll of FP4+ from the original batch of cannisters, and it came back. Even later still, I used a roll of FP4+ from a new purchase, and it didn't return. My conclusion is that it was a manufacturing or handling defect of some sort.

I also assume that the shadows around sprocket holes were somehow related to the same cause. I have never seen them with self-loaded film (also FP4+) so I'm sure they cannot be the camera.

The edge marks:

I'm sure this is due to the reels I use. I get it from time to time with 35mm and 120 film so it cannot be the camera, cannisters, etc. It never intrudes into the image so I ignore it.

Diagnosing light leaks on 35mm (Leica M3, Jobo Tank)

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