Light leak on Horseman 6x9 roll film back

At least I assume it's the film back's fault (It's on a Silvestri H). It doesn't happen all the time. In fact, on a cloudy day when shooting shots in quick succession, there's absolutely no hint of leaks. But on a sunny day, I have been occasionally getting the typical banded leak shown. At the time, I was half-heartedly using the dark slide to cover the slide opening when taking shots, but I'll be a bit more conscientious from now on.

However the location of the band might indicate that the dark slide hole has nothing to do with it. So I was just wondering if other Horseman users had run into this typical light breach at all.

Thanks in advance.

Evan

Looks exactly like some light leaks I had in my Horseman 6x12 roll film backs. The problem was in dark slide slot. The light trap material (felt?) got worn and no longer closed the gap when the slide was removed. Shine a bright flashlight into the slot and see if light comes through.

I had the light trap material in my backs repaired. Another option is to leave the slide partway in when making an exposure to keep the gap light tight. Mark the dark slide with a line so you'll know how far to pull out the slide and not block the opening for the film. This is how some of the Polaroid and Fuji instant film backs work.

konakoa said:

Looks exactly like some light leaks I had in my Horseman 6x12 roll film backs. The problem was in dark slide slot. The light trap material (felt?) got worn and no longer closed the gap when the slide was removed. Shine a bright flashlight into the slot and see if light comes through.

I had the light trap material in my backs repaired. Another option is to leave the slide partway in when making an exposure to keep the gap light tight. Mark the dark slide with a line so you'll know how far to pull out the slide and not block the opening for the film. This is how some of the Polaroid and Fuji instant film backs work.

Click to expand...

Thanks for that. Nailing down the likely cause is half the battle.

I bought a tiny LED light to test things in total darkness. Placed it in two separate spots: once in the film holder itself, and then in between the lens and the dark slide. I also put a bit of tin foil in front of the lens to spread the light around. With the light in the film holder, I couldn't detect any leaks. But when I placed it between the dark slide and the lens -- and when I pulled the dark slide out -- there was clearly a leak. And not only in my 6x9 holder, but also in the 6x7. And the leak was also present -- though not quite as much -- when the dark slide was pulled 80% or 90% out of the holder (as suggested by konakoa). So I'm thinking that I might attach a small flap of black velvet somewhere on the unit. Then I can quickly pull out the dark slide, but just as quickly cover the slot with velvet. Too bad that dark slides weren't mat black instead of shiny steel.