[Jimmy794]

Hi

I bought a secondhand Canon EOS 3 which the previous owner said was in perfect working order. Everything seemed fine but half way through the first roll the shutter seemed to jam. After a while it worked again, but then the autofocus seemed not to work properly, and the viewfinder seemed dim. It couldn't find focus or got the wrong focus. After a while I rewound the roll and fired the shutter a lot and this seemed to cure it. 

Does anyone know what is likely to have caused this and if it will happen again? Thanks 

[Klaus]

Hmmh, dark viewfinder smells like something with the depth-of-field preview or aperture control - both would dim the viewfinder.
As far as the jamming is concerned - the camera has probably barely seen any use in recent years. That may have had some side effects on the motors.

[Brightcolours]

I guess you mean the shutter button stuck? Now that it works again, you know it can get stuck on the down position, I guess. The dim view finder and AF issue sounds like the lens' aperture did not open up, got stuck. That then is a lens issue, not a camera issue.

[toni-a]

Does this happen with all lenses or just one lens ?? Seems mostly like a lens issue to me with aperture or flex cable problem

[wim]

Have you tried using a new battery?

I have an EOS-5 analog camera, and that did this when the battery was very low.

HTH, kind regards, Wim