Need help chasing light leaks!!!

[Scott --]

Okay, I've used this holder many times with no problems. Shot a sheet in it today, and ended up with this:

http://farm6.static.flickr.com/5275/5878212598_2c1e12deaf.jpg (http://www.flickr.com/photos/scott--/5878212598/)
Stupid leaks... (http://www.flickr.com/photos/scott--/5878212598/) by Scott -- (http://www.flickr.com/people/scott--/), on Flickr

A friend suggested I'd tugged the holder when pulling the darkslide. Wanting to assure myself it wasn't the camera, yet not wanting to throw away another expensive sheet of 10x12 film on what may be a suspect holder, I loaded a holder that I completely reglued and retaped yesterday. Ended up with this:

http://farm7.static.flickr.com/6024/5878632958_043f74c2f8.jpg (http://www.flickr.com/photos/scott--/5878632958/)
more_leaks (http://www.flickr.com/photos/scott--/5878632958/) by Scott -- (http://www.flickr.com/people/scott--/), on Flickr

The leak is all along one side of the sheet, and bleeds into the center somewhat, but does not bleed all the way to the outside edge of the sheet.

Anyone able to suggest what may be causing this? That second one makes me think there's a problem with the camera. Both of these were shot in subtle, but not quite dim, light.

Thanks,
Scott

[Mark Woods]

I think you're right about a problem with the camera. You could take off the lens board and put a bare light bulb into the bellows and see if you see some light. You probably should do this with the film holder in place.

[Scott --]

Okay, here's what I found:

Most immediate to the problems, one corner of the back when in portrait orientation has a pin that's almost completely buried in the frame. That corner lifts away from the back when the holder is inserted. Have to pull the pin and replace it.
There's a significant leak along one edge of the front standard where the bellows meets it. Caused by a screw not seating properly. Easy fix.
Each side of my three holders has a very slight leak along the top when contacting the back. May glue a piece of felt into the top of the back, but the leaks are so slight, I don't know that I wouldn't be making things worse.
Two of my holders have a corner in the light trap where the felt is leaking.


I think the problems today are from the corner of the back lifting, but I have a laundry list to work on now...

[ac12]

Since the same is happening w a different back, by elimination it must be the camera.
Use enlarging paper from here on, lots cheaper than film when you have to do several tests. You just have to expose the camera to brighter light for a longer time.

Dang you did a quick troubleshooting. And sounds like you did a pretty decent job of it as well.

[Mark Sawyer]

I think you're right about it being the back; maybe it wasn't seated firmly?. The light seems to be coming across the film at a steep angle, so it's near the rear of the camera. Filmhoders don't leak along the sides, which is where yours looks like it's coming from. Mark's idea about a bulb inside the camera is good, but use a CFL (they're cooler!). Alternatively, load photo paper in a filmholder, take it out on the sun, take the darkslide in and out a few times, then develop and check that for leaks. Paper is cheaper than film, though less sensitive.

Good luck with it...

[Ash]

Looks like the camera. Either a corner or a pinhole

[Mark Woods]

CFL is better! If the slot where the dark slide is isn't quite light tight, keep them in the dark and when you pull the slide, put your dark cloth over the back of the camera. I do this as a normal procedure whether the holder leads or not. Good luck on your fixes!

[Scott --]

Thanks for all the input, everyone. I have the camera leaks fixed. Used a cisel to wedge the back pin out of the wood, filled the hole, redrilled, and reset the pin. Works perfectly now. Removed and reinstalled the screws in the front, snugged them down well, and that's fixed. I think the very slight amount of light coming around the holders is negligible; that said, I need to get back in the habit of throwing a dark clot back over the thing when shooting. Used to do that, but somehow stopped... :rolleyes:

Hope to drag it out and try it again today.