Light Leak in 8x10

[Paul]

Hi,

I recently developed a light leak in my Tachihara 8x10. It varies, but is about 1 to 3 inches long. The leak looks like little fingers of density extending from the horizontal edge of the film, usually towards the center. It occurs at the top of the photo (the sky side), thus the leak is at the bottom of the back. I suppose I could confirm this by rotating the back so that up is down and see if the leaks appear at the bottom of the photo under those conditions, but have yet to do that.

I am pretty sure that it a problem with the back.

I do not think it is the bellows, since it is in good shape and I also rarely extend it past the 305 mm I need to focus my lens at infinity.

It occurs regardless of the film holder I use and is not a problem that occurs during loading or processing, since the rebate area of the film is fine.

This is a new problem. I have only noticed it on my last two outings. I exposed the last four shots I took with the darkcloth over the camera back, but I was worrying about the top of the back and not the bottom, so light could have come in underneath the camera. Plus is is one of those crappy Calumet horse blankets that is not completely opaque.

If, as I supect, the back is the culprit, what can I do? Could I use clamps and clip the darkcloth at the top and bottom to make sure the back is sealed and seated? Wait and hope it is warped and will unwarp with a weather change.

Any thoughts appreciated.

Thanks,
Paul

 

[Donald Miller]

I would begin by checking the camera in a dark room. Remove the lens board and insert a light into the camera from that opening. With the bellows extended, have a film holder inserted and check for light leaks to appear outside the camera. That will tell you more about what needs to be addressed.

 

[Paul]

Thanks, I will give that a shot. I am pretty sure it has to do with the seating of the film holder in the back. A month or so I noticed that the holder was not seating in the lower left hand side. I had to wiggle it to get it settled. I paid no attention to it at the time other than to make sure it had seated itself before I removed the dark slide. Tat particular day I had the camera set up in deep shade. Thus I suspect slight warping is the culprit. The springs seems tight.

 

[Paul]

I figured it out. I took the camera into a dark room as suggested and put a light inside it with a film holder in place. I could see a crack of light along one side where the holder does not appear to seat perfectly. It was tiny, but I could make it worse by pressing on the back a little from the inside, and I could make it go away by pressing on the back from the outside.

As a remedy I intend to:
make sure the back is well seated;
press on the back when removing and inserting the film holder;
cover the back carefully with at least a darkcloth and perhaps an added towel for moral support.

I think I may also invest in a View Camera Store darkcloth or something akin to it since that can be wrapped around the camera back completely.

-Paul

 

[light leak]

Oooh I would love to see Light Leak in 8x10!

 

[Paul]

May you never be so lucky.