Is it me, but difference between test strips and final output

Discussion in 'B&W: Film, Paper, Chemistry' started by hoffy, Sep 30, 2012.

  1. hoffy

    hoffy Member

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    Greetings,

    To get costs down, I have decided to give Arista EDU ultra paper a try. So far, not too bad, but I have a question and concern.

    I was printing @ around grade 3.5 and noticed that I was getting differences between what I had done with the test strips and the final print - I.E., I chose my spot on the test strip, tallied up the time and then made a final test strip. Based on that time, I was getting quite a difference in contrast (more) and started lose detail in the highlights.

    Would this be because of the one up exposure, instead of incrementally building up to the exposure time?

    Cheers
     
  2. eddie

    eddie Subscriber

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    Yes, I believe you have your answer. If I recall correctly, Fred Picker addressed this issue. 10 3 second exposures is not the same as one 30 second exposure. It's because of the amount of time the lamp needs to get to full brightness, and how it dims at the end of the exposure.
     
  3. randyB

    randyB Member

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    I too have experienced this, but with different papers. There can be other factors involved. To actually answer your question, yes, just what you said, five 6sec test exposures is not the exact same as one 30 sec exposure. After I determine what time to use (from the test strip) I then make another test strip, slightly larger in size to check if it is the final correct time, if not then I adjust. Other factors could be: #1 the way the paper handles the threshold exposure, #2 age of your bulb, as bulbs get older they can vary in their output even as they are burning, #3 most of the time the developer temp doesn't play a big role with this problem but it could contribute, as we all know, crap happens. Most of the time I chalk it up to being a charactistic of that paper and make adjustments on the fly. Be sure to fully develop and fix your test strips before making a determination of time/contrast. I also pull my test from the fixer tray to check as the fixer solution can alter the "look" of the print.
     
  4. tkamiya

    tkamiya Member

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    Are you saying you are making smaller print to test and using numerical calculations to arrive at an exposure for larger size?

    I've tried this also. While they come close, to me, it wasn't close enough. One time, I scaled up 8x10 to 11x14. Even at this modest change in size (x2), I had to decrease exposure from calculated figure and increase contrast to get the visual impact about the same. I think our mind is playing a trick on us.

    I also tried using test strip to get a local exposure right and do the whole print. It has only served me as a guide.
     
  5. hoffy

    hoffy Member

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    Thanks for confirming that - I have to admit that I have not noticed it as much when using Ilford papers (or maybe not as noticable).

    Cheers
     
  6. Griz

    Griz Member

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    Hi Hoffy, I noticed similar problems myself when going off of test strips, which led to the following, some excellent reading:

    http://www.michaelandpaula.com/mp/onprinting.html

    Using the outflanking procedure has streamlined my process immensely.

    Griz :smile:
     
  7. ROL

    ROL Member

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    Yes, when making test strips, or a test print, it is wise to expose in the time increments used rather than summing them up for one exposure (i.e., 4 sec. X 8, as opposed to 32 sec.). Also, some lamps, particularly cold lights, will change intensity and color as their temperature varies. Make sure they are warmed up before judging exposures.

    But I don't do much test stripping, just a test print, whereupon I begin printing the entire image. Smaller selections of the print (i.e., test strips) may in fact be exposed exactly the same as the full image and yet appear quite different, because the entire print needs to be judged in terms of its exposure, tonality, and contrast – not just the perfection of selected portions.
     
    Last edited by a moderator: Sep 30, 2012
  8. polyglot

    polyglot Member

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    Lamp warmup/cooldown means the light is redder at the beginning and end of an exposure, which means that multiple short exposures give lower contrast and lower density than one longer exposure.
     
  9. hoffy

    hoffy Member

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    Thanks for the comments everyone - it seems so obvious when you sit down and think about it and its obvious that it has always been happening. I just really noticed it with the Arista paper
     
  10. ic-racer

    ic-racer Member

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    To make one of those "stepped exposures" on the paper, you need to guess at the correct time so the steps straddle that guessed time. I don't waste my time on that "stepped exposure" anyway because the premise of evaluating different exposures on different parts of the image does not make sense to me.
    Anyway, after guessing at the exposure, just put a small piece of paper down and expose and process that. Go from there, lighter or darker etc. It lets you evaluate the same part of the negative with each 'test strip'.
     
  11. polyglot

    polyglot Member

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    This, a thousand times this. I don't get how people try to judge exposure by looking at different exposures on different parts of an image. Much better (though it takes a little longer to make the exposures) to make a bunch of test tiles - they each cover the same critical area of the print (e.g. a highlight or face or whatever) and each gets a single exposure of the appropriate length in the test-sequence.





    (apologies for the thread-hijack hoffy)
     
  12. Valerie

    Valerie Subscriber

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    This is an issue we see constantly in the class darkroom. An exposure in 5-2sec increments is different from a 10 sec exposure. I warn the students, but the lure of a single push of the "print" button is sooooo tempting!
     
  13. Slixtiesix

    Slixtiesix Subscriber

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    I don´t use the "stepped exposure" method. Instead, I expose the same part of the image several times on the test stripe, using different exposures. (eg. 5, 10, 20, 40 sec). I use a sheet of cardboard with a rectangular hole about 1x3" cut in the middle for this. This allows me a better comparison of the result (on the same part of the image) and eliminates the issue with the lamp warm up time. The test stripes are always 100% like the final result with MG IV. With fibre paper however, there is still the dry down effect...
     
  14. RalphLambrecht

    RalphLambrecht Subscriber

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    it is ad vi sable to expose the test strip exactly like the final print, even including dodging and burning steps to make it reflect the actual process.