Unexposed strip at bottom of 8x10 negatives

[NHW]

Hi all, my first post.
I just shot 4 sheets of 8x10. Each one has a strip at the bottom that is unexposed. the strip is pretty uniform and straight and has got progressively smaller with each subsequent shot. Started off at a good inch, now about half an inch. Ive no idea what's causing this. Hoping someone might. Many thanks.

[paulbarden]

Either you didn't pull the dark slide all the way out, or the bellows is sagging, intersecting the image area.

[NHW]

Thank you paulbarden. Probably bellows. I always take the dark slide right out.

[Doremus Scudder]

Set up for a shot, remove the back and look. You'll see if the bellows are sagging into the image area. Many bellows have a D-ring on a strap in the middle of the bellows that can be hitched up to a hook or whatever on the camera body just to combat bellows sag. Some people routinely prop up the bellows from underneath with a block or similar between camera bed and bellows (works only with field cameras). Larger cameras are more prone to bellows sag.

Best,

Doremus

[tgtaylor]

Compose your shot and then, before inserting the film holder, look through the lens. If any part of the bellows is intruding, you'll see it. If you see all 4 corners of the GG, you're set.

Thomas

[Kevin Crisp]

Carrying a small rectangle of dry mounting board is useful. Just stick it sideways between bed and bellows and it will straighten out.

[Robert Opheim]

Check the ground glass corner cutouts after stopping down to make sure nothing is blocking the full coverage on the film plane - and that the iris is round

[NHW]

Check the ground glass corner cutouts after stopping down to make sure nothing is blocking the full coverage on the film plane - and that the iris is round

Many thanks all. Mystery solved! All advice gratefully received.

[Duolab123]

Carrying a small rectangle of dry mounting board is useful. Just stick it sideways between bed and bellows and it will straighten out.

Oh yeah this a good tip.