Weird hot spot in the middle of my film (4x5)?

Discussion in 'B&W: Film, Paper, Chemistry' started by BHuij, Mar 5, 2018.

  1. BHuij

    BHuij Member

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    Took my 4x5 out to the park yesterday to photograph some new snow. I only exposed two negatives. Both came back with the centers a few stops thinner than the rest; like a radial gradient had been applied. See attached pics. I can't even begin to guess what might have caused this.

    Frame1:
    Frame1.jpg

    Frame2:
    Frame2.jpg

    -Both frames are FP4+, loaded at the same time into two different film holders, from the tail end of a box of 25 sheets that has given me no other problems. The box of film has lived in my fridge for several months, and these sheets were loaded into film holders just an hour or so before they were exposed. Film holders were kept in a dark pocket of my camera bag until time of exposure, as usual.
    -Both were taken with my 90mm lens, which has also never given me any problems. Frame 1 was taken facing almost directly away from the sun, frame 2 was taken facing almost directly into the sun.
    -Frame 1 was shot at f/11 using an orange filter. Frame 2 was shot at f/22 using no filter.
    -Both negatives were exposed within 25 minutes of each other.
    -Both negatives were souped using my normal method, at the same time, in the same Beseler color tube on rotating base, using the same chemistry (250 ml of Rodinal 1:100 to be precise).
    -I can't think of a time when either negative could have been exposed to a light leak of any kind, let alone one that would affect frame edges but not the center.

    To be clear, the center shows slightly less than expected density (about a stop), while the edges show 2-3 stops more than expected density (so about 3-4 stops more than the center).

    Anyone have insight to offer?
     
  2. Theo Sulphate

    Theo Sulphate Subscriber

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    Any chance of condensation on the lens or film sheet itself at the time of exposure?
     
  3. Ces1um

    Ces1um Subscriber

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    That'd be my guess too.
     
  4. jnanian

    jnanian Advertiser Advertiser

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    did your film stick together when they were processed ?
     
  5. Doremus Scudder

    Doremus Scudder Member

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    What I'm seeing looks like a lot of flare/extraneous light except for the middle area, which to me seems more correctly exposed and about the right contrast. I wouldn't characterize this as a "hot spot," rather a "foggy halo."

    I'd be looking for light leaks somewhere along the line. Check camera bellows, camera back, lensboard, loading/unloading area, etc. Do check the rebate of the film for fogging. If it is fogged, the fogging is likely out-of-camera and vice-versa. Condensation on the lens may cause this as well, in which case the rebate of the film will be clear.

    Doremus
     
  6. OP
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    BHuij

    BHuij Member

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    I'll have to do some investigation.

    I think I can rule out:
    -Filter light piping or any kind of weird flare effect (same effect happened with filter and no filter during exposure)
    -Fogged film before/during loading. Rebates look great, nothing there but FB+F.

    Most likely condensation. It was humid outside and cold, and I also loaded the film straight out of the fridge instead of giving it 15-20 minutes like I normally do. Most likely either condensation on the film itself or on the lens somewhere.

    I'll take the rig out again and see if I can eliminate the issue by allowing enough time for the film and glass to acclimatize to ambient temperature. If the problem persists, it's probably my bellows or lens board.
     
  7. OP
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    BHuij

    BHuij Member

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    Nope; everything stayed separated. I think the way I use the Beseler color tubes makes it pretty near impossible to have two sheets overlap; I only ever put one on each side of the tube. Never had one come out before during normal souping.
     
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