Mamiya C330 with black bar on the bottom of some frames

How does the negative look like? This sounds that the negative might have been misaligned during printing process and the black bar is the empty space between frames (lab fault).

I was worried about that, but I wanted to blame it on the camera or myself first -- this was my first roll of 120 film in a new camera. The negatives have the bar too -- it isn't just on the prints (and it isn't every print). Is it possible that the hand crank or my cranking skills could have something to do with the defect?

Afton

Can you post an example?

I'm wondering if the back shutter was getting in the way-- the thing that shields the film when you're changing lenses. Am I out to lunch?

Let me retract that-- back shutter comes up from below, so it would affect the top of the image field first.

The Mamiya TLRs have in-the-lens diaphragm shutters so that would not cause a black bar. A scan of the negs would be useful. If the black bar has a soft edge then it's probably the baffle (that;s the thing that swings up when you unlock the lens to change it) that has got in the way - have a look at the lock/unlock knob on the side. Is it in the 'lock' position?

Haven't looked at the baffle, but the lens Lock is in the lock position. Is it possible that I just didn't crank all the way? And, as I said, the bar isn't on every frame, and it isn't the same size. (Noticeable on 4 out of 12.) The key, I think, is that the entire image is shifted up -- I was doing timed exposure shots on a tripod, so there's no question that the image shift is real (camera didn't move, as I was using a cable release).

If you did not crank all the way, you should see a frame overlap or frames very close to each other. However, the full 6x6 frame should be still exposed. Also, the shutter locks and won't release until you wind enough film (the crank should come to hard stop when the film is successfully wound).

As for the baffle, it's spring loaded and should not stay in intermediate position. Also, the shutter locks if the baffle is up or midway. At least how it works on my C330s, there may be fewer interlocks on plain vanilla C330.

It would help a lot if you could post an example of the problem, it seems to me that we are all guessing here.

Here are some rough and ready scans -- adjacent frames, one with the bar, one without, and the camera didn't move between shots (locked down on a tripod).