light band across the top of neg

Discussion in 'Black and White' started by mattalofs, Mar 13, 2004.

  1. I just push processed a roll of HP5+ in DDX to 1600. It turned out fine
    except for a light colored stripe across the top 2-3 mm of the neg. It
    runs the whole length of the neg. It isn't real noticeable; it kind of
    looks .5 less exposure or something similar. Any body out there seen
    this before? Can I avoid it in the future? Thanks in advance.
     
  2. Is it possible you didn't have quite enough developer solution to completely cover the reel?
     
  3. I thought about that possibility, but I used the exact same amount as normal. If I didn't use enough dev I also would have expected the top edge to have no development, right?

    Another thought that occurs to me is that it might some sort of temperature difference between the top of the developer and the bottom. But I would have expected a more gradual transition in that case.
     
  4. If you agitate by inversion, you would expect that the band across the "top" would be less well developed - not completely undeveloped. Also, if you agitate in just about any way, there will be little to no temperature variation in the developer. Odds are, you just didn't use as much solution as you think you did. I hate when that happens ;-)
     
  5. There's another possibility here, which is that (depending on your camera) it might be a shutter problem. If your camera has a vertical focal-plane shutter (i.e. exposure moves the curtains from top to bottom, rather than left to right), a second curtain that's binding on the first, or a slow starting first curtain could lead to underexposure at the beginning of travel (which would normally be image bottom on the negatives); a first curtain binding just before it clears the frame could lead to underexposure of the bottom (image top) of the frame. Binding is more likely than a spring problem, because it would have to be a sharp change in curtain speed to cause the kind of well delineated light area you're seeing.

    Did you accidentally poke your finger into the shutter while loading film recently? A bent edge on a cloth shutter curtain, or a bent leaf in a metal shutter, could bind in exactly the way, and for just about the right distance, to cause what you see.

    Another point to check -- is the edge of the thin area relatively sharp and straight in each frame, but varies a tiny bit from frame to frame, or is it fuzzy and slightly wavy in all frames but pretty much the same height in all? If the edges of the affected area are all straight but they vary in height by a fraction of a millimeter, randomly from one frame to the next, it's a shutter problem. If they're fuzzy, wavy, and vary only slowly (as if, say, the tank had stood on a slightly tilted surface), then it's solution volume.
     
  6. Can you scan the strip of negs so we can see the problem?
     
  7. I'm fairly sure that the shutter is fine on the camera. A roll developed 10 minutes later didn't show the same band.

    I don't use inversion agitation; my tanks have a rotating agitator.

    I probably just didn't get enough dev in the tank, but I want to believe it's a much more complicated, less stupid mistake.

    I'll scan in a couple of frames next week when I can use the neg scanner at work. I probably repost the question then. Thanks to all that responded.
     

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