Plus X anomaly?

Discussion in 'B&W: Film, Paper, Chemistry' started by Fred Aspen, Mar 27, 2009.

  1. Fred Aspen

    Fred Aspen Member

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    I processed a single roll of 35mm Plus X in D-76 1:1, water stop, and TF-4 fix. Half the roll was exposed at 80 and the other half at 125 because of lighting conditions.

    The frames exposed at 80 have a distinct brown cast/stain while the frames exposed at 125 are the normal blue-gray appearance and what I normally expect.

    I have never noticed this before.

    Thanks!

    -F.
     
  2. George Collier

    George Collier Member

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    Are the frames grouped into to sets by exposure? (eg, first half at 80, second half at 125), or did you go back and forth between lighting situations?
     
  3. Fred Aspen

    Fred Aspen Member

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    First half at 80, second half at 125. I think I read somewhere that TF-4 fixer is prone to brownish negs, but I can't find the reference.

    -F.
     
  4. Matthew Gorringe

    Matthew Gorringe Member

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    Very strange Fred,
    My Plus-X negs are quite brown but I had assumed it was the Pyrocat-HD that was making them so. I've only ever processed them in Pyrocat-HD and like you I use a water stop and TF-4 fix. I expose it at ISO64 and place imortant shadows on Zone 3.

    It's really interesting that the extra exposure seems to be what's making them go brown. Does the base fog look blueish or brownish?
     
  5. Fred Aspen

    Fred Aspen Member

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    The base fog on unexposed film is clear and slightly bluish.

    -F.
     
  6. Matthew Gorringe

    Matthew Gorringe Member

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    In paper processing image tone is said to depend on the size of the grains in the emulsion with smaller grain being warmer and larger grain being colder.

    Could it be that Plus-X has enough of a difference in grain sizes in the one emulsion that less exposure will favour the larger, more light sensitive and bluer grains and more exposure activates the smaller, less sensitive and browner grains?
     
  7. DWThomas

    DWThomas Subscriber

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    I guess I've not done a series where I would have had the opportunity to notice that. Since the negs shot at lower EI were brown, I wonder if it's just a denser build-up of brownish silver particles overcoming the blues/grays of the base and emulsion? Are the more heavily exposed negatives visually more dense?

    DaveT
     
  8. Fred Aspen

    Fred Aspen Member

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    DaveT, yes, the negs exposed at 80 are visually denser than the negs at 125, about 2/3 stop, as would be expected. I think you are on to something as I checked a couple of other rolls shot at 80 and they have the brownish cast. It is not too noticeable unless you have a mixed roll, then they are very noticeable. BTW, I use d76 original formula, hand mixed. Perhaps the brownish cast is an indicator that the film is being overexposed by some amount.

    -F.
     
    Last edited by a moderator: Mar 28, 2009
  9. Jim Noel

    Jim Noel Member

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    Pyrocat stains proportionally to the amount of reduced silver. I am wondering if the extra exposure is putting enough extra light on the film to cause the staining effect of the developer to be more apparent. If so wouldn't this indicate overexposure?
     
  10. Fred Aspen

    Fred Aspen Member

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    That is exactly what I was thinking as well. But 2/3 of a stop doesn't seem like much overexposure unless PX is that sensitive. I have never noticed that before.

    BTW, the camera is a recently CLA Leica R4S in manual mode.

    -F.
     
  11. erikg

    erikg Member

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    I was thinking dev. stain too, but this film was processed in D-76 was it not?
     
  12. Fred Aspen

    Fred Aspen Member

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    Exactly! Processed in D-76 mixed to the original formula. Maybe the original formula has some staining characteristics. I'm baffled!

    -F.
     
  13. Fred Aspen

    Fred Aspen Member

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    I just finished a roll of 400TX in the same developer and the heavily exposed part of the leader has a brownish cast to it. I also develop for a condenser enlarger so I am thinking that it is the combination of more exposure than the minimum needed and slight under (incomplete) development (-20%).

    -F.
     
  14. Fred Aspen

    Fred Aspen Member

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    Okay, I violated my own (and Anchell's) rule. Anchell's rule: 250ml of stock to fully develop film to its maximum capability. (Paraphrased from Film Developing Cookbook, pp. 31. Up to this latest roll I had been following his advice.

    Snip test in the last half hour:

    D-76 1+1 ten minutes = faded, brownish (still able to see through) fully exposed leader.

    D-76 straight five minutes = virtually opaque (but still a very slight brownish cast) fully exposed leader.

    My conclusion: 125ml of stock D-76 in 250ml of working solution isn't sufficient to fully develop a 24 exp. roll of PX, using times/temps from the B/W Darkroom Dataguide.

    If anyone can find fault with my logic/experiment, please don't hesitate to set me straight.

    Thanks!

    -Fred.
     
    Last edited by a moderator: Mar 28, 2009
  15. wogster

    wogster Member

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    I think the issue is the brown colour, D76 isn't a staining developer, maybe your D76 is past it's prime....
     
  16. Fred Aspen

    Fred Aspen Member

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    Just mixed the day before from chems fresh from the formulary.

    Unless there was some unexpected contamination, but the same developer used undiluted works fine. I think I will go back to TMAX developer, not worth the hassle. No probs with TMAX or Rodinal.

    -F.