Praktica MTL3 Double exposure and film distance problem

fullbuster79 · Sep 2, 2015

Hello,

I'm pretty new to film photography and I have some issues with my camera.
I noticed that the distance between my photos on the film gets bigger as the photos advance. For example the firs 3 pictures have somewhere around 1 cm distance between them whereas the last photos have somewhere around 3 cm or more. Also I noticed that the last photo from the film is always double or triple exposed.
So because of this lots of photos are ruined and at the scanning process the scanner cuts pieces of them. Also I can't know when my film is over.

I attached two photos for a better example.

Kind Regards!

John Koehrer · Sep 2, 2015

It could very well be that the clutch on the wind spool is at fault. It has to slip when the film is rewound but not slip when it's advanced. Access to it would be under the advance lever and wind gearing.

AgX · Sep 3, 2015

It has to slip at advancing too.

The turning of the take-up spool is geared for the situation of an empty spool. During taking up more film it has to slip via a clutch.

AgX · Sep 3, 2015

But at an MTL the advance is controlled by the sprocket wheel anyway. And that should run at fixed rotation by construction.

I assume the disengadgement of the sprocket wheel (for rewinding) by fault is on constantly and the film is transported instead by the take-up spool. Which leads to a frame spacing that is growing and too large from the beginning.

Though that would not explain those double exposures.
I assume thus that disengaging variably affects just the sprocket wheel or the whole transport chain, which would lead to the result you have got.

fullbuster79 · Sep 3, 2015

That might be, I forgot to mention that the double/triple exposed photos were always the last ones.
Is there any way to fix this?

AgX · Sep 3, 2015

Normally at the end of film there would we resistance via the sprocket wheel at the transport Lever. (Further engaging it would lead to tear of perforation) indicating that the film has come to ist end.

In case of by fault film being transported by the take-up spool, at the end of the film that clutch, that I described above, comes into action. You will feel not much more resistance and erroneously expose one frame onto the other in sucession.
At least that shows the fault is a little bit more simple than I indicated at the end of post #4...

If I'm right there is nevertheless something wrong at the transport mechanism.
To repair that you should have knowledge about it. Your initial question already showed that you have not.

Maybe some Praktica repair specialist chimes in and can guide you through an repair attempt.
But for having it repaired most likely, seen the prices of Prakticas, it would be a economic loss.

fullbuster79 · Sep 3, 2015

Yes I just noticed that when I keep the camera in a straight position, like when you would take a photo, the sprocket wheel doesn't move completely but if I hold it to face the ground it works as I suppose it should. So if I lift the sprocket wheel a bit up it works properly in a normal position.

AgX · Sep 3, 2015

Thus some gear is lose and only engages the sprocket wheel depending on the position of the camera, otherwise the take-up spool takes over film advance with result described above.

As economically you have nothing to loose, you might try a repair attempt... and learn something about camera innards...
As said someone might guide you through it. First issue would be removing the top cover.

fullbuster79 · Sep 3, 2015

I removed the top part but couldn't get a clear view of the sprocket. I managed to solve this issue by placing a small piece of metal at the baae of the sprocket so it would keep it in place. Untill now everything seems fine. I will test it with some film to see how it goes.

Thank you a lot for your replies!

AgX · Sep 3, 2015

I did not realize that the issue is situated at the base of your camery (sprocket wheel bearing).
But I wonder that the film did not keep the sprocket-wheel in position, sufficient enough to be engaged by its gear train.

Xmas · Sep 3, 2015

It is probably the grease is 30 years old and has turned to wax.

The latch that you clear by pushing the rewind button is not resetting properly (completely) when you wind on, as it should.

You may be able to clear by removing the base plate and dripping zippo down the inside of the sprocket shaft an operating the wind on while the wax is more compliant. Try to catch and excess with cotton waste. Then adding one drip of watch makers fine oil.

Repeat until ok on a cold day.

fullbuster79 · Sep 3, 2015

I suppose the sprocket would slip just enough so the wheels were not in contact. It wasn't moving that much, some few millimeters I believe.

Xmas · Sep 3, 2015

The sprocket can be part of the latch mechanism you need to reverse engineer the latch parts to see where the grease is causing the problem. If it works with your shim that is a clue.

ic-racer · Sep 3, 2015

AgX said:
and the film is transported instead by the take-up spool.

^^ This ^^

The sprocket is disengaged when rewinding film and may still be disengaged. I suspect the problem my lie in the button or lever used for film rewind.

fullbuster79 · Sep 3, 2015

Yes, that was the consequence of the problem, but I saw that the problem was in the contact between the sprocket's wheel and the lever's wheel. Sometime's, usually when the camera was held in a normal position, the sprocket's wheel would slip out of lever's wheel. I'm not sure if this is actually how the mechanism works but that's how I imagined. I suppose it is some kind of simplified version.

Xmas · Sep 4, 2015

fullbuster79 said:
Yes, that was the consequence of the problem, but I saw that the problem was in the contact between the sprocket's wheel and the lever's wheel. Sometime's, usually when the camera was held in a normal position, the sprocket's wheel would slip out of lever's wheel. I'm not sure if this is actually how the mechanism works but that's how I imagined. I suppose it is some kind of simplified version.

The mechanism can vary but the simplest which is what you may have are done concentric with the sprocket shaft itself by having a device which slides axially to allow the outer part of sprocket shaft to spin Independent of the inner for rewind or lock them together for next frame.
Wax in the mechanism won't allow it to operate properly it needs to move freely driven by low tension spring
Your shim is helping a little by constraining the outer part of the concentric.
You need to get zippo into the sprocket shaft carefully, and absorb it at the other end of shaft on cotton, cause stripping it is major disassembly - normally.

Praktica MTL3 Double exposure and film distance problem

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