Canon AV-1 - shutter capping repair

Does anyone know how to fix shutter capping in a Canon AV-1. The problem is more apparent at higher speeds (the picture is probably taken at around 1/500s-1/1000s), but it's noticeable on almost all pictures even at lower speeds.

I'm pretty certain the second curtain is faster than the first one. Would I be correct that this can be fixed by slowing down the second curtain?

I'm happy to open up the camera and l've already done so, but my problem is I don't know which screw is used for the second curtain. There is not that much info on the AV-1 and it's a different layout from the AE-1. I read the manual for the AE-1 and I'm confident I could fix my camera, but I just don't know which screws to turn.

If anyone has any pictures or knows which direction to turn which screw, I would greatly appreciate.

Are you sure the first curtain is not just slowing down as it reaches the end of its travel? I would assume the shutter tension is still whatever it was set to by the factory and that something else is causing the uneven exposure - something that won't be fixed by adjusting curtain travel speed. In fact, I would expect that, even if adjusting the speed did fix the problem, the problem would soon return.

The second curtain will not speed up on its own, but the first curtain may be slowing down due to dried lubricants or some kind of junk in the gears or track.

The problem

Don_ih said:

Are you sure the first curtain is not just slowing down as it reaches the end of its travel? I would assume the shutter tension is still whatever it was set to by the factory and that something else is causing the uneven exposure - something that won't be fixed by adjusting curtain travel speed. In fact, I would expect that, even if adjusting the speed did fix the problem, the problem would soon return.

The second curtain will not speed up on its own, but the first curtain may be slowing down due to dried lubricants or some kind of junk in the gears or track.

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The problem with uneven exposure is on the right side of the image. The curtains move right to left, so either the first curtain is zooming past the right side of the imagine (which I think it’s unlikely as that would mean lower exposures on the whole film since it starts on the right side) or the second curtain is faster and it closes sooner than expected (the lower exposure on the right side which is the one that closes second).

I tested the shutter speeds with the slow mo on my phone and it seems relatively okay, but I can only film up to 240fps so it’s hard to tell at higher speeds where the issue is more apparent. I might build the shutter tester that’s been posted here, but that would only tell me if there is a problem, not how to fix.

Been trying to find a repair manual, but no luck.

My point is that the reason it's happening will have nothing to do with the curtain tension, since that likely has not changed since it left the factory. Adjusting tension may fix the symptoms of the problem but it won't address the cause, which will likely continue to get worse.

Don_ih said:

My point is that the reason it's happening will have nothing to do with the curtain tension, since that likely has not changed since it left the factory. Adjusting tension may fix the symptoms of the problem but it won't address the cause, which will likely continue to get worse.

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Do you know what might fix the issue? The camera is really clean inside, there is no dirt, grime or corrosion on anything and the only issue I found was some dried up oil at the bottom of the plate. I bought a journal from learncamerarepair.com, but it's only 3 pages covering the AV-1 and there is no info on lubricating the gears or slow/out of sync shutter. Should I just try putting a small amount of watch oil on the curtain gears?

Below is the shutter speed readings from the camera using this technique (https://www.photrio.com/forum/threa...al-plane-shutters-cheap-easy-it-works.197756/).



According to the repair article in the journal, the curtain travel time should be 10.5±0.3ms, so the timings are all pretty good until 1/500.

I wish I could help. My only guess is that something is releasing the second curtain before it should be. That would account for the faster slow-shutter speeds while having the normal (higher) speeds be slow.

In general, you don't put oil on gears since it eventually turns to mud.

I have seen first curtains that were sluggish opening and the second curtain released before the first curtain opened. But only on cameras where the first curtain released mechanically via the mirror and the second curtain released via an electromagnet.

I presume , since the AV1 is aperture priority only, it may work similarly.

Don_ih said:

I wish I could help. My only guess is that something is releasing the second curtain before it should be. That would account for the faster slow-shutter speeds while having the normal (higher) speeds be slow.

In general, you don't put oil on gears since it eventually turns to mud.

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After cleaning all the magnets and eliminating that possibility, and after doing A LOT more research reading forums from the early 2000s, it seems like the issue is/was relatively common with the A-series and it could possibly be that the shutter bearings and rollers lubrication has dried up and gunked up the system.

Some resources for others that might face the same issue:
Another example
Different camera, but same issue and the same advice is given that it might be the shutter bearings that need lubricating: https://www.flickr.com/groups/41721319@N00/discuss/72157636348007966/

That said, does anyone know what these bearings/rollers look like in an AE-1/AV-1/A-1 or where they should be located?

ic-racer said:

I have seen first curtains that were sluggish opening and the second curtain released before the first curtain opened. But only on cameras where the first curtain released mechanically via the mirror and the second curtain released via an electromagnet.

I presume , since the AV1 is aperture priority only, it may work similarly.

Click to expand...

As far as I can tell, the AV-1 has an electromagnet for the first shutter release and another one for the second release.