Inverted Light Leak?!

Hey guys,

 

I encountered a problem and was hoping somebody might have seen it before and can tell me if my suspicions are correct and my lens is somehow broken. I got hold of a Canon 35-70mm f4 FD Lens for my A1, which looks good and does work without issues on multiple shots but when stepped down quite a bit (probably above f8) theres a huge area that is heavily underexposed.

 

 

It is definitely nothing in front of the lens or inside the body that is blocking the light either, most of the shots of the roll are fine.

 

This is what the aputure blades look like... I feel they should be more evenly round then they are, or am I wrong?

 

 

Testing on a digital camera with adapter works without issues on all aputures, although they do not close when I take a picture.

 

Did someone see this problem before? Is the lens one for the trashcan?

 

Thanks a lot!

I'm not sure what this is, but I don't think it's a lens problem so keep it out of the trash can for now.

This is a problem with the camera, not the lens. The shutter curtains seem to be moving unevenly at the the slower speeds which would be needed at smaller apertures.

This is a problem with the camera, not the lens. The shutter curtains seem to be moving unevenly at the the slower speeds which would be needed at smaller apertures.

 

I really hope you’re wrong :((

 

Most of the pictures of that roll were shot a the fastest shutter the camera offers (1000th), the ones that show the problem were definitely shot at that way though!

This is a problem with the camera, not the lens. The shutter curtains seem to be moving unevenly at the the slower speeds which would be needed at smaller apertures.

 

I looked into it a bit - I'm afraid you're right and its shutter capping...

 

Does someone have a source on how to address the tension of the shutter springs and maybe even get to the parts that might need lubrication on a Canon A1?

Just a guess but you possibly need to clean the magnets ...

 

"Essentially take the bottom off the A1 and clean the second-curtain electromagnet surfaces."

The reason I said it was happening at slower speeds was that the pictures were said to have been done at small aperture. It's definitely a problem with the highest speed, with the curtains coming together during their passage across the frame, as you have now observed. I can't help with a fix. If you stick to 1/250 and slower speeds you should be OK.

Most of the pictures of that roll were shot a the fastest shutter the camera offers (1000th), the ones that show the problem were definitely shot at that way though!

In that case it's almost definitely the shutter. Shutter 'stutter' nearly always affects the higher speeds.

 

And there's no way that a lens aperture fault could cause that banding effect.

 

Sorry, but you just have to accept that most film cameras are old, and don't last forever. The shutter can possibly be cleaned and adjusted, but probably at an uneconomic cost.

 

The timing solenoids simply control the release time of the first and second curtain. They'll have little effect on the second curtain catching up with the first during transit. That's due to the first curtain dragging or having insufficient spring tension.

 

The cure is to ensure the track of the shutter is clean, and that the bearing rollers are also clean and free-running. If dirt or sticky bearings aren't at fault, then the blinds need re-tensioning. It's best to slack both springs off and re-apply the tension to both blinds, rather than just wind one or both springs tighter.

Edited June 4, 2020 by rodeo_joe|1