Mamiya 645 Uneven exposure with line dividing negative

[snark]

Aha. This is why I post problems like this one here, for the expert opinions. Thanks all. I've just learned that a light leak through the shutter would not normally fog the film side to side; didn't know that. So it has to be the back. I would have gone there to start with but for that first test roll I ran through the camera without changing lenses. No problems on that roll. The only difference between that test roll and the later ones with the fogging, was that I changed lenses on the latter. Wish I had written down when I changed lenses on my exposure sheets, but I did not record that datum. Looks like I'll have to experiment, make copious notes, and isolate this problem by process of elimination. I'll let you know what I find. Good night...

 

[480sparky]

......, make copious notes,.........

This might help you.

 

[snark]

I am really a dinosaur. An anachronism, if the truth were said. I don't have a smart phone, just one of those clamshell things that makes phone calls and really lousy pictures. But thanks anyhow, I will incorporate some of the ideas into my hard copy record sheets that I fill in with...a pencil.

 

[Derrel]

So...this light-leakin' Mamiya....maybe you can learn a thing or two by reading the Holga user pages here...Edmund and Sophie s Photo Page Holga Tips

and here Loading a Holga Camera Freestyle Photographic Supplies

Or...pretend it's a camera made by Microsoft....those light leaks are not a bug--they are a FEATURE!!!!

 

[snark]

It rained all day yesterday so I had time to fool around with my old Mamiya. Thinking this problem we've been talking about was a light leak, I loaded a new roll and held the camera close to a bright light at all angles and under different conditions (lens cap on/off, lens on/off the body, back taped/not taped) between tests advancing the film with the lens cap on. After I had tried every combination I could think of, I fired off the remaining frames out the window into the rainstorm. The shutter speed was consequently slow on all of those, 1/30 sec. When I developed the roll there was no fogging of any kind.

I conclude that I do not have a light leak. I'm thinking sometimes, probably at faster speeds, the shutter is slow and overexposes the whole frame, and sometimes it hangs up momentarily part way through its travel and overexposes only part of the frame. Sometimes it fires properly and I get a good exposure. This might explain why I cannot find any common denominator among all the problems - it doesn't happen predictably like a light leak would. Does this make sense? If so, anyone know what's involved in fixing this shutter? Or do I start looking or another camera body now that I own a new anchor for my boat?

 

[snark]

More to report - I was working the mirror lock up lever back and forth and found the mechanism has a stiff point about halfway. I'll bet dollars to donuts that's the problem. The camera is what...45 years old...and probably needs CLA. In the meantime until I find someone to do that, I guess I will tripod mount the camera and use it in the mirror lock-up mode.

I was googling around and found a ten year old thread on another site in which someone else was asking about the same problem. So my trouble is apparently not unique. I hope the info in this thread helps someone else, so I have edited the title to make it a little more specific. Thanks all, for your assistance.

 

[Derrel]

I would start by firing the shutter a number of times at about 1/250 second...say 10 times, then go down to 1/60 second for 10 frames or so, then go down to 1/8 second and fire 10 frames or so, then go down to 1/4 and 1/2 second, which you can almost "time out, mentally"....see if the shutter seems "sticky" at 1/2 second...perhaps the gear train is just gummed up with old, hardened lubricant. Normally, the faster speed will shoot okay, but slow speeds can be "sticky", and slow...see if 50 to 100 frames of dry-firing will get things loosened up.

 

[vintagesnaps]

That's what I've found on old cameras, the slow speeds can be sticky and the faster speeds seem OK. I listen and can at least tell if it sounds way slower than it should be. Those are for display or if I use them I do so on a nice sunny day so I don't have to use the slower speeds! Obviously I need something accurate to use for purposes other than playing with the camera.

Now, what kind of donuts are we talkin'?

 

[Derrel]

MAPLE BARS!!!!!!!!!