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  1. #481

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    I've been pondering recent results:

    * Concentrate 119P (aka Trial 20130119) (uses Phenidone) gives a hint worse grain with Tri-X than XTOL. With Delta-400, 119P is a hint better than XTOL.

    * Concentrate D316 (also uses Phenidone) gives the same or a hint better grain with Tri-X than XTOL. This tells me that the higher level of ascorbate (or lower pH) improves grain with Phenidone.

    * Concentrate 119D (same as 119P, but uses Dimezone S) gives slightly better grain with Tri-X than XTOL. That tells me that in this dev, Dimezone S is superior to Phenidone.

    * Concentrate 214D (uses Dimezone S) gives significantly better grain with Delta-400 than 119P, and somewhat better than 119D. This tells me that the higher level of ascorbate (or lower pH) also improves grain with Dimezone S, and Dimezone S is already better than Phenidone. Here's a comparison of 214D and 119P with Delta-400:

    119P: Click image for larger version. 

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ID:	64541 214D: Click image for larger version. 

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    214D is my best developer so far. Its formula is:

    Propylene Glycol ..................... 12.2 g (grams, not ml)
    Sodium Metaborate 4 mol ...... 1.8 g
    Ascorbic Acid .......................... 4.2 g
    Dimezone-S ............................ 0.08 g

    A litre of developer contains 18 g of concentrate and 45 g of sodium sulfite with pH = 8.08.

    The only difference between 214D and 212D that I posted a few days ago is that the Dimezone S in 214D was reduced to .08 g (instead of .09 g). This change makes the ascorbate/Dimezone ratio match XTOL. At this point, I plan try tweaking the amounts of metaborate and/or ascorbic acid to drop pH a little, and see what that does. Then I'll decide on a formula and run a bunch of tests on it. BTW, I found it wasn't necessary to resort to hydroquinone, because all the ascorbic acid still dissolves in this concentrate despite the lower level of metaborate. But I still want to try TEA instead of metaborate -- if the ascorbic acid will dissolve, it'll provide an interesting alternate to metaborate.

    Actually, my tests show that the amount of Dimezone S makes little difference. 0.07 and 0.09 gave the same curve and grain as 0.08. I figured this meant the dev is regeneration-limited instead of dev-limited, so I reduced the ascorbic acid while keeping pH the same and surprise: It made no difference in dev-speed. I know sulfite also helps with regeneration, so perhaps it's the limiter? But I'm keeping sulfite at 45 g, which is half of what XTOL has, and doubling dev-time (by reducing pH) to get the same solvent-effect.
    Good news: This insensitivity to Dimezone-quantity means that you can be sloppy about measuring Dimezone S. Sub-tenth-gram quantities are difficult to measure accurately without a milligram scale, so it's good to know that you can be 10% off and still be fine.

    I was reminded that the supply of Dimezone S for us home-brewers might be unreliable. Alfa Aesar synthesized a batch, which Photographer's Formulary sells, but when that batch runs out, it's anyone's guess if they'll synthesize a new batch. Therefore, I suggest that you buy 100 g of Dimezone S from the Formulary. The price is reasonable, and that will give you a lifetime supply.

    Mark Overton

  2. #482
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    Mark;

    The synthesis of all of the Phenidone family of developers is rather straightforward. So, if there is a market, it might still be made. It depends on the size of the market.

    As for the attached images, do my eyes deceive me or is the Dimezone S example less sharp? That would explain the apparent lower grain.

    PE

  3. #483

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    Sharpness is such a difficult thing to evaluate in this way. Mark, perhaps some sort of image evaluation test is in order to supplement the grey patches. Just a thought when it comes to the tradeoff between graininess and sharpness.

  4. #484

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    Michael R and PE: The patches were not in perfect focus, so sharpness is impossible to gauge. I switched to another lens which eliminated the problem of corner-falloff. But the sharpness of that lens isn't the best. As was pointed out before, contacting is the best way to do this, and I need to build a fixture that will let me contact wedges onto 35mm film.

    BTW, these developers have similar chemistry to D316, so I figured sharpness will be similar to D316, so I didn't worry about it. But it would be good to be able to check sharpness anyway...

    The fine grain of 214D surprised me. At first, I thought the scanner must have been misfocussed, so I re-scanned the neg -- with identical results.

    Mark

  5. #485

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    Quote Originally Posted by albada View Post
    .......Good news: This insensitivity to Dimezone-quantity means that you can be sloppy about measuring Dimezone S. Sub-tenth-gram quantities are difficult to measure accurately without a milligram scale, so it's good to know that you can be 10% off and still be fine...................
    There was a post some time ago by Sandy King, the inventor of Pyrocat-HD, in which he said something similar. I think I remember him saying that if you went over a certain range you got excessive fog, and if under, weak development. But within a range, there was no difference.

  6. #486

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    Dimezone-S can also be obtained from www.techcheminc.com. This is where I purchase my developing agents. They sell 100 gms for $25.00.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  7. #487

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    John:
    Good to know that I'm not the only one who has seen that odd insensitivity-to-quantity phenomenon. I was trying to change density by varying amount of Dimezone, and density wasn't changing. That took me by surprise.

    Jerry:
    That makes it three sources of Dimezone S. I looked at the price-list of TechChemInc: They're competitive. Thanks for mentioning them.

    Ron:
    I scanned Tri-X strips, shown below. Same result: Grain is finer with 214D than with XTOL. But I included the bottom edge of the wedges so the Mackie lines would show. They're about the same. Also, I looked at edge-markings in loupes, and both XTOL and 214D are neatly outlined with black (Mackie) lines of similar density. So it appears that sharpening is comparable. Below, the 214D scan is on the right. The left scan is XTOL with slightly higher contrast than 214D, and the middle is XTOL with slightly lower contrast than 214D. Grain in 214D is a bit finer than both. To make the comparison fair, all three scans have been digitally adjusted to have equal contrast.

    XTOL1: Click image for larger version. 

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ID:	64640 XTOL2: Click image for larger version. 

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ID:	64641 214D:Click image for larger version. 

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    Here are the graphs of these three strips:

    Click image for larger version. 

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    214D shoulders off later (black line), as usual for these D316-like developers. That should help folks who shoot in contrasty lighting, such as mixed sun and shade.

    Mark Overton

  8. #488
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    Great results Mark.

    Thanks.

    PE

  9. #489

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    Alan Johnson was kind enough to mail me the negatives from his D316 longevity tests. He used D316 that was 2 months old and 12 months old. As he said, he was rough on the developer, storing it in a 90%-empty bottle at room-temperature, and opening it for a half-hour each month. So that was a worst-case test, resulting in dark orange concentrate. I measured the neg's on the densitometer, and I calculate that 30% more dev-time was needed. From this, you can estimate how much to increase time for various shades of colouration. Here are the time-increases that I would estimate:

    clear -------------> 0%
    yellow -----------> 7%
    dark yellow -----> 15%
    orange ----------> 22%
    dark orange ----> 30%

    I suspect these numbers are good for 214D and similar, not just D316. Also, I suggest freezing the concentrate in storage: Hopefully it will stay clear for a year, and you'll never need to increase the dev-time.

    Mark Overton

  10. #490

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    As well as that test for oxidation I hope to do a test to find if phenidone/dimezone-s will hydrolze by reaction with the water of crystallization in one of these developers.
    To speed up the reaction it is intended to place full sealed bottles of concentrate on top of a hot water tank ~40C.
    Hydrolysis of phenidone produces phenylhydrazinopropionic acid: C6H5.N.CH2.CH2.CO.NH +H2O -> C6H5.N(NH2).CH2.CH2.CO.OH
    Not a lot of people know that.



 

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