Test For Light Leaks--Graflex RH20 220 Back

[wjlapier]

I need a quick way to test for light leaks. I have a Graflex RH20 220 film back I need to test for leaks before I use it with 220 film. I figure I can use 120 film and "move" some of the backing paper to the end of the film and attach with tape so the paper will wrap around the film after advancing past frame 20. Could I just cover the lens and advance like I would normally, in bright sunshine, to check for leaks around the back? I'd develop and fix I guess to see if there are light leaks on the film.

Where the hinge and latch are there is some sort of fabric I'm assuming was the original light seal. I don't see any other light seal material on the back.

I could add some light seal foam to the channels and around the area of the hinge and latch (I did this with a RH8 back and no leaks. ).

What do you think?

 

[shutterfinger]

With the insert in the shell check for play in the latch and hinge. Black yarn is used for the light seals.
With the holder attached to the camera, remove the dark slide and lens. In total darkness shine a bright light into the camera through the lens mount while observing the holder. Point the light at the edges of the holder, hinge, latch, and dark slide slot. Anything other than BLACK is a leak.

 

[wjlapier]

I think there is a leak from the dark slide side. I quickly shot a roll of 120 ( prepped it like it was a roll of 220 ). There is the slightest sign of a leak in some photos on the right edge of the photos. A couple photos didn’t have light leaks because those shots I left the dark slide in part way.

I’m taking a Mamiya Universal flat top with the 50mm lens on vacation soon. I have a RH8 back that has no leaks so far. I’ll use that back mostly. I have one roll of 220 in the RH20 with tape over the dark slide opening. And some tape on the hinge to make sure.

Thank you for your suggestion on how to look for the leaks.