Switch to English Language Passer en langue franaise Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 71,829   Posts: 1,582,211   Online: 1024
      
Page 3 of 4 FirstFirst 1234 LastLast
Results 21 to 30 of 34
  1. #21
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,821
    Images
    10
    Out of sheer curiosity I tested this developer with a test clip contact exposed through a Stouffer wedge. I have not scanned in the clip, but from looking at it I'd say that with 5 Minutes development at 30C the clip is seriously overdeveloped. We have every reason to believe that the alleged speed increase is an effect of this overdevelopment.

    Alan, can you confirm that you used anhydrous form of Sodium Sulfite and Sodium Carbonate for your test? I did and seem to get significantly higher b+f density than what you showed here.
    Trying to be the best of whatever I am, even if what I am is no good.

  2. #22

    Join Date
    Nov 2004
    Posts
    1,178
    http://www.digitaltruth.com/devchart...ch&TempUnits=C
    I developed APX 100 for 6min 20C.
    Is your 30C a typo?
    Carbonate and sulfite were anhydrous from a reputable supplier of photochemicals, Dimezone-S was from Moersch, Vit C from a health food store.

  3. #23
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,821
    Images
    10
    Quote Originally Posted by Alan Johnson View Post
    http://www.digitaltruth.com/devchart...ch&TempUnits=C
    I developed APX 100 for 6min 20C.
    Is your 30C a typo?
    I do my test charts at 30C in order to speed up testing. Yes, if 7 minutes at 20C is indeed the correct processing time for Xtol stock and Tri-X, then I should repeat this test either with 6 minutes at 20C or 2 minutes at 30C. But looking at the contrast of this neg, I think the threefold increase in dev time alone doesn't explain the huge contrast I got.
    Trying to be the best of whatever I am, even if what I am is no good.

  4. #24

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    5,083
    I can try a test this weekend and plot the results if it would help. Unfortunately I don't have the film Alan used though. I could maybe use something non-exotic like FP4 since I have other reference curves for that film in XTOL and DDX. But I'm not sure what development time to try here. Based on the quantities of developing agent in W3, and its pH, I would expect it to behave more like a print developer in terms of activity and with high fog since it definitely (my opinion based on the formula) needs a restrainer. W3 contains the kinds of quantities we'd normally see in a stock print developer before dilution to working strength.

    I'm still wondering why it is so strongly formulated. Perhaps I need to better understand the goal of W3. Is the intention to make a long lasting concentrate, or is it just to increase speed over D-76? Etc. Some thoughts:

    -Phenidone film developers with superadditive secondary agents typically only contain a fraction of the amount in W3, even developers formulated for speed increases.

    -There is a lot of ascorbic acid present, and at a pH of 9.8 it might be doing more than regenerating the Dimezone-S. For a speed increasing developer, it is usually desirable to try to keep contrast under control, but the formula as-is seems like it would produce high contrast.

    -There is a lot of carbonate present, which would tend to make W3 highly buffered, which would tend to further promote contrast.

    -To control fog, I suspect a significant quantity of BZT would be required in W3, which would tend to reduce speed and further promote contrast.

  5. #25

    Join Date
    Nov 2004
    Posts
    1,178
    Quote Originally Posted by Rudeofus View Post
    I do my test charts at 30C in order to speed up testing. Yes, if 7 minutes at 20C is indeed the correct processing time for Xtol stock and Tri-X, then I should repeat this test either with 6 minutes at 20C or 2 minutes at 30C. But looking at the contrast of this neg, I think the threefold increase in dev time alone doesn't explain the huge contrast I got.
    Yes, thanks for noting.

    10% less than Xtol 1+0 time is not correct for all films.

    It seems about right for APX100 but some Acros I developed in W3 for this time was somewhat contrasty and overdeveloped.
    I would expect about EI=80 for Acros with D-76, attached pics of a cable duct and some silver birch trees were taken at EI=125, have plenty of shadow detail overdeveloped in this way (in error).
    The fact that Acros was overdeveloped does not mean that there is no speed increase with correct development. Chemically it is similar in composition to the former Paterson FX-50 but more concentrated in the working solution:
    http://www.photomemorabilia.co.uk/Pa...testreport.pdf

    Michael,
    My theory is that these phenidone/ascorbate type developers kept in half full bottles usually fail because all the ascorbate is oxidized and/or the pH drops.
    To get round this I use a lot of ascorbate that can cope with a lot more air and a lot of carbonate as there is a lot more acidic decomposition products to be buffered against.
    Yes, if you get around to doing the test you mention it certainly would help to clear up the matter of the film EI vs some other developer.
    Attached Thumbnails Attached Thumbnails w3 4.jpg   W3 5.jpg  

  6. #26
    Rudeofus's Avatar
    Join Date
    Aug 2009
    Shooter
    Medium Format
    Posts
    1,821
    Images
    10
    Alan, if you look at the definition of contrast index (see page 9), which is/was also used for ISO speed determination, you see that a density of 0.1 over b+f level is used as threshold. If you look at the typical curve, there is discernible detail below b+f+0.1, and forced development will make this extra detail visible in enlarged prints.

    So yes, you will gain a bit more shadow detail with push development. We should still not call this "speed increasing", because speed is defined for a specific C.I.
    Trying to be the best of whatever I am, even if what I am is no good.

  7. #27

    Join Date
    Nov 2004
    Posts
    1,178
    In view of the very short development times I have given up the attempt to use the concentrate.
    Instead, a 1-shot 1+9 dilution is tried.
    Provisionally, APX-100 developed 6min 20C in this gives an EI at least 160 and the grain and tonality are improved.
    Results to follow.

  8. #28

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    5,083
    Alan, I mixed 500ml of the concentrate and was going to try it out on some Delta 100. But with the 1+9 dilution I'm not really sure what development time to try. I guess I could try 6min as you have done, but at this dilution the working characteristics will be significantly altered. At the working dilution the formula now bears more of a resemblance to compensating-type developers, which may help with an effective speed increase. I'm still expecting relatively high fog though, given virtually any Phenidone developer with a pH this high uses a restrainer.

    I will see what I can come up with in the way of sensitometry, but I wonder if this development time will even be in the ballpark.

  9. #29

    Join Date
    Nov 2004
    Posts
    1,178
    Michael,
    http://www.photomemorabilia.co.uk/Pa...imes_2002.html
    Times for Delta 100 and APX 100 in FX-50 are very similar.

  10. #30

    Join Date
    Feb 2010
    Location
    Montreal, Canada
    Shooter
    Multi Format
    Posts
    5,083
    I just did a test with Delta 100. Development time (1+9 dilution) was 7:00 at 68F. Given the high alkalinity, initial agitation was one minute. This was followed by my usual "standard" agitation (1-minute intervals).

    The attached graphs show the gross D (including fog but excluding film base) and net D relative to the normal contrast curves obtained with XTOL. Obviously contrast in this trial with W3 was too high. Some combination of reduced development time, more dilution or less agitation would be required. However this would likely also mean reduced speed, which is already approximately equal to XTOL. Fog was measured approx 0.08 higher than XTOL developed to normal contrast. W3 fog level would be expected to decrease somewhat if developed to a lower gradient.

    Experiments with other films would be required. This result with Delta 100 is reminiscent of the type of response I got when I tried TFX-2 with it. TMax 100 seemed to respond better to that developer.

    Perhaps I should have tested W3 with a more traditional reference emulsion such as FP4. I still have the rest of the concentrate I mixed.
    Attached Thumbnails Attached Thumbnails W3.jpg  
    Last edited by Michael R 1974; 03-08-2014 at 10:48 PM. Click to view previous post history.

Page 3 of 4 FirstFirst 1234 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive     Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin