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  1. #501

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    Quote Originally Posted by Rafal Lukawiecki View Post
    Thanks, Mark. Out of interest, do you prepare Dimezone S in propylene glycol so as to make it easier to measure such a small amount, or do you just use 0.001 precision scales, which would really mean 0.0001 precision, I suppose? I can see how making the concentrate can be a better proposition, overall, for the consistency of measurement.
    I do both.

    I usually mix 2 litres worth of concentrate, and that's enough that I can measure Dimezone S directly using my .001 resolution scale. But for small tests, I use Dimezone S mixed with propylene glycol in a 2% solution like this:

    Propylene glycol .......... 49 g (grams, not ml)
    Dimezone S ................. 1 g

    Then, to get X grams of Dimezone S into a developer, where X is a tiny number, I weigh 50X of that solution, which is much more accurate.

    Mark Overton

  2. #502
    Rafal Lukawiecki's Avatar
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    Thanks Mark. I wish I had 0.001 scales, but I have been using 0.01 so far. An upgrade may happen but your approach in PG makes more sense. I will research how does Dimezone S keep in PG, to avoid failure, and waste.
    Rafal Lukawiecki
    See rafal.net | Read rafal.net/articles

  3. #503

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    PE will be interested in this.

    With 400-speed films, developer 214D produces a curve whose shape matches that of XTOL (example below), but is shifted down slightly. This shift doesn't matter when printing or scanning, but it makes the ISO-defined film-speed drop. Here are the curves for Delta 400. The left graph is the original curves; the right graph shows the 214D-curve shifted up by .02:

    Click image for larger version. 

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    In the left graph, the 214D-curve crosses the Y=.1 line (.1 above B+F) about 1/2 stop to the right of the XTOL-curve, causing an apparent speed-loss of 1/2 stop. But the shifted curve in the right graph shows their shapes differ insignificantly. So how do I determine film-speed if a vertical curve-shift skews the ISO-number?

    Long ago, the ISO standard used a superior method of determining film-speed called "Fractional Gradient" (FG). Stephen Benskin knows all about this. People complained that it was hard to calculate because you had to plot the curve, so ISO changed the standard to an approximation used to this day. I estimated the FG speeds for 214D, and always got at least 400 speed for 400-speed films. It's too bad that today's ISO method punishes a developer for shifting a curve down a little.

    If you look at the right graph closely, you'll notice that 214D has a slight speed-loss wrt XTOL, but it's so small that I'll trade it for the finer grain I get. And the FG method says I'm still getting at least 400 speed, so I don't care. Or should I care? Any idea why this brew shifts the curve down a bit?

    Some Test Results

    Here are results of my testing so far. At a prior poster's request, I'm emphasizing low speed films because they gave Ryuji's DS-10 trouble. Pan-F+ failed with DS-10, but does fine with 214D (and D316).

    Film Time
    Tri-X 13.5
    Tmax-100 13
    Delta-100 12.25
    Delta-400 18
    Pan-F+ 12.25
    FP 4+ 16
    HP 5+ 15

    In my testing, I've seen two things worth noting:
    1. The small downward curve-shift described above with 400-speed films.
    2. An early shoulder (compensation) with Tmax-100. D316 did this too. Don't overexpose it. This compensation would be useful for compressing wide-scale scenes, but the cost you pay for this feature is lack of overexposure-latitude. This only applies to Tmax-100. All other films behave normally.

    As always, comments are encouraged.

    Mark Overton

  4. #504
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    Mark;

    There is a slight error in the shifting of the curves, but no matter. The point is that if the curves are identical in terms of speed as viewed on these curves, then if they print identically, then the speeds are the same. This is one of the faults in measurements of ISO like this.

    PE

  5. #505

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    I'm almost done testing 214D, and I plan to post a report about it in the articles section when done. Just need to develop a roll of Delta 3200 that I shot this evening.

    But T-Max 100 (TMX) gave interesting results: It shouldered off early. In another thread, Drew Wiley said this happens to TMX with several popular developers. So I mixed 214P, which is the same formula, but using .05 g of Phenidone instead of .08 g of Dimezone S. Here are the curves of both with TMX:

    Click image for larger version. 

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    Phenidone (green curve) pushed the shoulder out a little, maybe 1/2 stop, and the shouldering isn't as severe. But what's odd is that Phenidone's shoulder is a sudden change of slope. In fact, the green curve is two straight lines. That makes me wonder if the shoulder is actually due to the low-speed emulsion taking longer to develop and thus giving a lower slope in the highlights. But only with some developers.

    Also note that Phenidone gives a small apparent speed-increase (per ISO-definition), but at the cost of a softer toe.

    Anyway, my advice is: If you shoot much TMX, use Phenidone and accurately shoot at box-speed. Else use Dimezone S.

    Mark Overton

  6. #506

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    Quote Originally Posted by albada View Post
    Wow; it's been awhile since I posted the formula. Here it is:
    Propylene glycol ................. 16 ml
    Sodium metaborate 4 mol ..... 2.2 g
    Ascorbic acid ..................... 4.5 g
    Phenidone ......................... 0.05 g
    .....
    Here are times in minutes at 20C:
    .....
    Mark, what about dev.time for this formula? same as XTOL stock/diluted or other?

  7. #507

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    Quote Originally Posted by Relayer View Post
    Mark, what about dev.time for this formula? same as XTOL stock/diluted or other?
    The formula you quoted is for an earlier developer called D316. I changed it a little and am temporarily calling it 214D. Its formula is:

    Propylene glycol ................. 12.2 g (same as 11.8 ml)
    Sodium metaborate 4 mol ..... 1.8 g
    Ascorbic acid ..................... 4.2 g
    Dimezone S ....................... 0.08 g (or use 0.05 g of Phenidone)
    A litre of developer contains 18 g (same as 15.4 ml) of concentrate and 45 g of sodium sulfite. pH is 8.08.

    The times for this are posted four postings ago on this page (scroll up). If you decide to try it, please post your results. As I mentioned earlier, I plan to post an article about this concentrate after finishing testing.

    Mark Overton

  8. #508

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    Quote Originally Posted by albada View Post
    The times for this are posted four postings ago on this page (scroll up).
    as I found last formula with same time as XTOL is http://www.apug.org/forums/viewpost.php?p=1370427 ? why you change to twice diluted version?

  9. #509
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    When I was dealing with Dimezone S a few years back, I had batches lose activity. Fresh Dimezone S would return prior performance, then seemingly lose activity again. 3 sequences had me feeling pretty confident about the Dimezone link to the behavior. Have others had this happen or was I somehow getting batches at the end of their useful life? I became disenchanted at the time and hadn't returned to it (partly from having some success with concentrates in PG right about then and being told that Dimezone S had its main advantages in water-based mixtures). I recall searching out ways to extend its life but didn't discover anything at the time that seemed to show promise.

    I'm open-minded about it but mainly curious about others' experiences that might mirror Mark's recent episode and what I had seen?
    Craig Schroeder

  10. #510

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    Mark, FYI attached are two curves with 35mm TMY-2 (same batch as you tested).

    Regards,
    Michael
    Attached Thumbnails Attached Thumbnails Untitled.jpg  



 

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