Originally posted by Gordon Coale
The slower speads worked fine but 1/250 and 1/500 did this. Underexposed and the right half with no exposure. A couple of frames had the funny red marks on the left. Any suggestions?
Hmm, could be a couple of things at work here. That sort of problem at high shutter speeds may be an indication of uneven curtain tension - in your case the closing curtain is going faster than the opening curtain, so the right (beginning) side of the neg is getting more light than the left. This is, of course, less noticable at lower shutter speeds. If I take the plate off the bottom of the shutter box of my Zorki 4, there are two screws that if I loosen, allow me to adjust the tension of the curtain take-up spools. I've never had to do this. You can see them in the last photo of this page
from Rick Olsen's web site.
You could probably do the TV trick to check this out. Remove the back and lens and look through the shutter at a TV (a channel of pure static works great). Because the TV "paints" one frame in 1/60 of a second, from top to bottom, when you trip the shutter at 1/250 you should only see a diagonal strip from Top right to bottom left of constant width, about 1/4 of full screen. If your strip narrows towards the bottom, you have a closing curtain that is going to fast. If it is fatter at the bottom, it is closing too slow.
Can you scan the whole width of a few frames? Does the "fog" extend beyond the edges of the frame?