This afternoon I put together a 5X7 back out of junk parts that were laying around. It's for an old Kodak 2D that found it's way to my house. It had a nice 4X5 back but no 5X7. So I put one together from Stuff that was in the junk piles.

After dinner I thought, I'd better check this assembled gobble-d-gook back and make sure things are lined up. Takes about 5 minutes, and it cracks me up that you guys will spend a gazillion dollars for some silver bullet outfit and never spend 5 minutes checking the most important thing. The film MUST be on the exact plane that the ground surface on your glass is at.

I used a rubber band, a torpedo level, and a thick business card. A credit card might be even better.

Lay the level across the back surface. Tap the biz card down until it sits flat on the glass. Carefully take it off and set it aside without bumping the card.

Insert a film holder with a piece of film in place, and set the level back on the same surface you started with. That card should just brush that film if everything's perfect. Both of the ones I checked were spot on. Remember, it doesn't have to be pretty to make pretty pictures.