Mamiya 645AFD Vertical Light Band on Negatives

LaGrassa · Feb 5, 2010

Some, but not all, of my negatives and prints have this light band that runs vertically about midway across the frame. Any idea what can be causing this? Thanks.

tkamiya · Feb 5, 2010

I'm not sure if it's really on the negatives or just a scanning artifact, but I see vertical strips and variation in exposure across the entire frame. It's just that the middle one is the most obvious.

cheuwi · Feb 5, 2010

check for light leak...
I had that happened to me and I eventually find a crack in my back.
Good luck.

LaGrassa · Feb 5, 2010

It's definitely on the negatives, so perhaps the light leak theory is plausible. Will check my backs.

unclemack · Feb 5, 2010

Numbering your backs and noting this on each film can be useful in diagnosis.
If the stripes are on the full film length the cause may be processing but the frame spaces should then show signs.
If it's only in the picture area then the shutter may not be running smoothly - any hesitation of the curtains can cause vertical striations (not usually so many though) with a horizontal-run shutter. Got to admit I'm not even certain yours is horizontal-run because I retired before it was built!
Holding just the camera body at arm's length facing a well-lit white wall and firing the shutter a number of times while concentrating on the film gate you can often actually see the vertical striation. If you try the higher shutter speeds first these are most likely.
If you have records of the shutter speeds used for the affected exposures this also aids diagnosis.

LaGrassa · Feb 5, 2010

Unclemack:

I have two backs, one I use for color and the other for B&W, and interchange them mid-roll sometimes. None of the color negs show this, but some do on the B&W negs, all taken on the same day. Other negs on that roll taken on a different day do not show this. Could it be that possibly not locking in fully the back while interchanging could cause this?

unclemack · Feb 6, 2010

Sorry but this site has just logged me out for the umpteenth (and last) time while I was replying - this nonsense is unacceptable to me.

David_A · Feb 6, 2010

The way I sometimes work these things out is to mentally put the film back into the back.
Dose the band go all the way across or just in the film frame?
If in the film frame only then maybe shutter related.
If all the way across then it’s most likely to be the back itself.

Then it’s a matter of working out where the light might enter, without knowing what the back looks like, I use the ETRSi, I can only give rough advice. Back closure area? Does it have a firm locking action which might have not gone home entirely? If so I would take a look at any light seals.
Another area to possibly have a look at is the way the film was processed, is the tank completely light tight?

David

LaGrassa · Feb 6, 2010

I am going to try the camera with a friend's ZD digital back and test the shutter operation. If that works out, then I think I can isolate the problem to one of the two film backs that I have.

Mamiya 645AFD Vertical Light Band on Negatives

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