Light Leak - Film Handling?

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I seem to have an intermittent problem that I think is occurring before/while/after loading 120 rolls film into my Mamiya 645. Here is a flatbed scan of one of the negs that it's happened on.

Although it's almost impossible to see on the scan, the extra density (I don't know what to call it!) goes across the frame and out right to the edges of the film (past the frame boundaries) and fades to the top of the frame. The more of these I look at, the less I think it's a loading problem (how 's that for an about turn!) as the films where that has definitely occurred are jet black (longitudinal edge marks). I have a couple of tests in mind that might isolate the problem to the camera or my handling of the film, but that will use film for no reason, so I thought I'd ask for opinions 1st! So... thoughts?

-- Nigel Smith (nlandgl@unite.com.au), January 11, 2001

Answers

Looks like your camera has a light leak. Your scan seems to show clear edges and interneg spaces, so the light must be coming in the front of the camera via a leaky shutter, bellows, or the like. Go in a dark room, open the camera back, put in a flashlight and cover the back as best you can, then examine the exterior of the camera for light leaks. Or stick your eye up to the open back and shine a strong light on the outside. Your saying it's intermittent suggests a mechanical problem than occurs now and then.

-- Keith Nichols (knichols@iopener.net), January 11, 2001.

Nigel, Mamiyas 645's are notorious for this. I would check the back plate on your film cartridge. It is a user replaceable part. If the screw holes develop a crack, you'll get light damamge.

-- Scott Walton (scotlynn@shore.net), January 11, 2001.

I will offer a bit more orthodox reason here. It could be leftover silver from developing. Try prewashing the film and then use fresh developer & fixer for the time specified and with the tempreture specified. Good luck

-- Nauman Saghir (nsaghir@hotmail.com), January 11, 2001.

Scott is exactly correct. Check the face plate on the interchangable back, it has a crack. You have to really check it carefully. The cracks are some time hard to see. Sometimes you have to move around the dark slide for the crack to reveal itself.

-- Pat Raymore (patrick.f.raymore@kp.org), January 11, 2001.

You've got me concerned about my own Mamiya 645 now, but I think we must be talking about a different model.
Which flavour of 645 is affected?

-- Pete Andrews (p.l.andrews@bham.ac.uk), January 12, 2001.


Pete, mine is a very old, battle scared 1000s

-- Nigel Smith (nlandgl@unite.com.au), January 12, 2001.

OK. So if it's a light leak through the pressure plate of the insert, how does the light get into the fixed back in the first place?
Nigel, I suggest you check the fabric light seal that covers the top edge of the mirror. It looks to me as if light might just be sneaking down the back of the mirror, through the viewfinder.
Do you only use the WLF? A prism finder might cure the problem.

-- Pete Andrews (p.l.andrews@bham.ac.uk), January 12, 2001.

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