Assuming both were developed by the same lab, I would probably run a short roll of B&W and develop it myself, but next closest idea would be shoot the cheapest color you can find and get it developed somewhere else. Then see if the problem persists. Or have you had recent good results from your lab with another 35mm camera? That is, it might not be your end.
I just dug my AE-1 out and can't say I have any "Aha!" moments looking at it. There is a film reminder widget on the back that holds a box top. It appears to be attached by some sort of rivets or plastic studs -- is all that in place? (Since it is behind the pressure plate, I doubt that could be it, but we're being rather challenged here!)
There are three small screws in the cassette end, two in the body and one in the cover -- are they all there? (Again, I think this is very unlikely, as the film is inside the can at that end.
In the take-up spindle end (right end from photog's perspective) there appears to be thin foam on both the body and the back, next to the hinge. On mine (unused in about a dozen years), there doesn't appear to be much left to flag that those were seals! What does catch my tired and ancient eye is that there is a gap in the tubular roll that forms the hinge, where I can see a shiny chrome pin/rod of some sort. I suspect the gap is access to retract the spring loaded pin to remove the back. It's about the right distance from the edge of the film to create your problem -- but being it's next to the take-up spindle, I would maybe expect the effects to vary a bit as the spool fills and the diameter changes. If those seals mesh, it shouldn't be a problem.
Assuming all the exterior components -- covers, shrouds, whatever are undamaged, it's hard to see where things might otherwise run amok. Does your camera show any signs of damage -- bent metal work or fumbled repairs?
My goto Canon FD is an A-1, so I don't have much AE-1 experience to go on. Shortly after my dad died, mom gave me his AE-1 and I did put a few rolls through it, but we're talking 1998 or so, and all was well at the time. I'd say the seals in mine definitely look a bit sketchy now.
I find it difficult to suspect the lens end, but do you have -- or can you beg, borrow or steal -- another lens to try a few shots?
Edit: There is a strip of foam across the front of the ground glass area that serves as a mirror bumper -- is that intact? (I'd think your strange spot is too sharply defined to be from that but since we haven't accounted for it .... )
(Hey! Maybe all this thinking will prevent Alzheimers! :D )
I don't have a camera like yours, but that red spot looks (in the second roll, not so much the first) like LED-light. Are there indicator lights anywhere in the camera, e.g. viewfinder display or flash-charged indicator?
Next possibility: is there a tear or thin patch in the shutter, e.g. at a fold? Shine a strong torch into the mount and into the viewfinder and see if you can see anything coming through the cloth.
This post makes me wonder - do you have a data back on the camera?
Originally Posted by polyglot
@MattKing - From what i can tell the camera back is the original and totally windowless, i handle my film from it arriving in the post, to lightproof box, to fridge, to camera and to lab so unless someone has pulled ye old switcheroo tis definitely the same camera :|
@DWThomas Great minds thing alike and i decided to run some tmax through it recently and develop it myself as a control, the marks where still there but fewer and further between, a fact i attribute to my tendency to use B&W film in lower light situations.
I had the same theory about the film type reminder window so that too was taped over in the grand insulating tape test.
Similarly i had noticed they spring pin myself only recently when i removed the door to re-seal it, but surely andy light coming in through there would have been protected when i taped it up (or at least drastically reduced).
I replaced the mirror bumper foam along with the seals on the door but i will certainly check, first time in a long time my camera hasn't had a roll in it so i will take it to my room of light (the darkroom that with a flick of a carefully guarded switch becomes the intensity of a thousand suns for inspecting prints etc) and look at ever square mm of the body for anything out of the ordinary.
Not many people i know have an FD canon but there is a shop locally which sells pretty much every camera between 1920 to 1990 (its heaven) and im sure i could persuade them to let me borrow one for the day if i left my DSLR as collateral :)
@Polyglot/MattKing There is an LED based warning for under/over exposure and also a red glowing M for non Av , i wil check the curtain later today.
Thanks so much for all your help chaps summer is approaching and a non light tight camera seems somewhat of a paperweight :)
I recently had a similar problem but in a Canon EOS 5. It turns out the that the shutter was at fault. As Polyglot asked, is there is tear in the shutter curtain?