Film Testing FP4+ in DDX

Discussion in 'Black and White' started by danalarsen, Jul 3, 2016.

  1. I've been going through the process of zone system testing for Ilford FP4+ 125 4x5. I'm using Ilfotec DDX at 75 degrees (because I live
    in Arizona). I develop in a Jobo CPP3 using a 3010 Expert Tank. I pre-soak for 5 minutes based on Jobo's recommendations, use 300
    ml of DDX, and equal amounts of Ifostop (10 seconds) and Rapid fixer (3.5 minutes). All density measurements are being made with an
    X-Rite densitometer.

    My film speed test gave me a .11 density at EI 100 and a .09 density at 125. This was based on using the manufacturer's recommended
    development time of 8 minutes for the 75 degree temperature. Since they're both so close to .10, I chose EI 100 as my go forward speed
    taking Adams' recommendation of using the higher of the two close numbers.

    Moving on to the N development test. I made three identical zone VIII exposures with accompanying blank exposures using the same
    setup used for the film speed test (full frame gray card focused at infinity in open shade). I'll cover the results of each below.

    1. Developed the first pair using the exact same procedure I did for the film speed test - 8 minutes at 75 degrees - my density minus film
    base + fog was 1.54. Because I'm using a diffusion enlarger, I'm shooting for 1.25 - 1.35. So I'm obviously too high using manufacturer's
    recommendation.

    2. Developed the second pair reducing development time by 20% which was 6 minutes 24 seconds at 75 degrees - my density minus
    film base + fog was 1.47. Still too high.

    3. Given the relatively low drop in density between trials 1 and 2, I took the third pair down to 5 minutes 20 seconds (the same time I use
    for HP5+ in DDX by the way). In this case my density came out to 1.40. Still too high.

    So now I'm getting concerned that to get to between 1.25 and 1.35 for normal development the times are going to be below 5 minutes
    which I've heard is not recommended in most cases. So I have several questions:

    1. Am I going overkill in trying to get down to that density range? I print exclusively on variable contrast paper (Ilford RC) and if I
    shouldn't be obsessing over 6 hundredths of a density measurement I'll stop.

    2. Is the higher 75 degree temperature speeding up development too much to enable me to get to these densities without risking
    development of the shadows?

    Any other thoughts about what I might be doing wrong. I've tried to be precise in my descriptions, so let me know if there is something
    that I'm missing.

    Thanks in advance.
     
  2. As long as you're dialing in for your specific equipment and temperature situation, I'd be tempted to at least try a slightly more dilute solution and see if you get the curve that you hoped for but not block up the highlights. I have just a little DDX experience but it was many years back but recall that it stood up quite well to moderate dilutions.
     
  3. I tried DD-X at 1+9, rather than the normal 1+4 dilution, with different 100 ISO films in the early 2000s (FP4 plus and Acros) in spiral film tanks (120 film) and had good results. I think the added time was something of the order of 40 or 50%. Ilford provides only 1+4 data.
    My darkroom process is less precise than yours. I do not measure densities and experiment less, but perhaps you might try dilution to keep times high enough and accept the trade-offs that dilution might bring.
     

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