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Thread: Pyrocat Tests and Some Disappointment?

  1. #31
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    Re: Pyrocat Tests and Some Disappointment?

    By comparison, here's part of a test that Fred Newman made for me a few weeks ago, of Ilford HP5+ developed in D-23 1:1 (not divided D-23).



    Note that this is a more diluted developer - and D-23 has a reputation as being low-energy - so the contrast range is much lower - but how much lower ? There's no guess work here.

    To get a normal Contrast Index of 0.5, we need to develop for 10 minutes. Also note that even after developing for 16 minutes, we still haven't reached N+2 expansion. This film/developer combination is probably great for a sunny day at the beach, but not for bland subject matter.

    On the other hand, with this film/developer combination, N-2 development happens at around 5 min 15 seconds.

    So not only do we know that this is a "lower contrast film/developer combination", we know exactly how low, and how long to develop it to get the contrast we want.

    There's no guesswork involved. Instead of relying on someone's well-meaning but vague advice (Person A: "I've been souping Plus-X in X-Tol 1:8 for the last decade. I really like it." Person B: "You gotta try Tri-X in PMK-XYZ at 3:2:1000. Nothing beats it") we get unambiguous facts we can really use, and a common language with which we can easily compare and categorize film/developer combinations.

    This isn't the whole story, though. We know that different film/developer combinations give different effective film speeds. But which one gives which speed ? Shall we rely on friendly advice ? ("Try pushing FP4+ to ISO 8000 and develop it in Nescafe - you gotta see it to believe it")
    Last edited by Ken Lee; 24-Mar-2012 at 06:06.

  2. #32
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    Re: Pyrocat Tests and Some Disappointment?

    Quote Originally Posted by sgutterman View Post
    If I don't get this sorted out satisfactorily I hereby promise I won't keep using Pyrocat. I'll switch to caffenol and post rambling diatribes about the inherent superiority of Folger's T-Crystal Structure as it affects transient...shadow...rendition...on the toe of the reciprocity...density transmission feedback frequency.
    That sounds awesome. Make sure you label the axies of your graphs in your report on this. And the US folgers might be different from the EU folgers.... And how the stain affects VC printing.

  3. #33

    Re: Pyrocat Tests and Some Disappointment?

    On and on about the negatives.

    What do the finished prints look like???

    If you still have not made any you are wasting your time and effort.

  4. #34

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    Re: Pyrocat Tests and Some Disappointment?

    Quote Originally Posted by Ken Lee View Post
    You don't have to buy one, unless you plan to test a lot of film or digital negatives.

    One thing I've learned by looking over the data which accompanies the purchase of the BTZS "Plotter" program (a number of films, in a number of developers, at various dilutions, for various times) is that they all look fairly similar. One gets the same impression looking through Ansel Adams' books, where it becomes evident that over the decades he used a wide variety of films.

    Some film/developer combinations are better than others of course - they have more linear response to light and changes development time - or better effective film speed. Some are easier to mix, have longer shelf-life, or are cheaper, but those are secondary features. Where they really differ most (in my humble opinion) is in terms of grain, spectral response, apparent sharpness, acutance, reciprocity, etc. When it comes to Large Format, many of those are irrelevant, and we can often make good use of just about anything... once we've tested it.

    You might find it very helpful to choose one film/developer combination and do a film test with Fred Newman at the View Camera Store. Then you'll know what you've got: independent of scanner, monitor, software, calibration tools, photo editors, Gamma settings, color spaces, ink sets, room color, etc. Hey, the digital world is supposed to make things easy
    The late Phil Davis used to do a demonstration at his workshops designed to show that choice of developer and developing methodology makes a much bigger difference in the look of the negative and ultimately the print than the brand or type of film used. Sorry I don't remember the details of exactly what he did but I think he did this in most of his workshops (I attended two and he did the same demo in both), maybe someone else does.

    I second your suggestion of using The View Camera Store to do testing. I've made the same suggestion here many times. They do it faster, easier, and likely for less money while providing more information than one spends doing their own testing. That said, doing one's own testing is an excellent learning tool.

    I'm not aware that "the digital world is supposed to make things easy." In my experience scanning and printing digitally makes things harder (but potentially better).
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  5. #35
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    Re: Pyrocat Tests and Some Disappointment?

    Quote Originally Posted by jp498 View Post
    Make sure you label the axes of your graphs in your report on this.
    And I thank Ken Lee for filling in that blank left in Sandy's article on the Unblinking Eye.

    Particularly: The meaning of contrast index, in terms of normal values, for people who did not read the BTZS book before reading the article on Pyrocat.

    Rick "who actually had to look at the Wikipedia article on sensitometry to understand the log-exposure axis--every 0.3 is a stop" Denney

  6. #36
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    Re: Pyrocat Tests and Some Disappointment?

    To be clear, a contrast index of 0.5 is normal for printing with Silver Gelatin.

    On the BTZS charts, the Contrast Index is listed as G with a bar over it, which means Average Gradient. It's the average slope of the contrast curve. In other words, given a certain amount of exposure, how dense the negative becomes. When contrast is low, even a lot of exposure gives little density, and the curve is rather flat: its slope or gradient is low. When contrast his high, even a little exposure results in a lot of density: the slope of the curve is rather steep, IE the gradient is high.

    Actually, Sandy's article has a table - at the top of the same page to which I have referred - which shows the recommended Contrast Index for different media.



    That table is another piece of information which is worth its weight in gold, as is the statement "Most processes have means to control contrast but it is good practice to always start with the best negative possible for the process."

  7. #37
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    Re: Pyrocat Tests and Some Disappointment?

    Some feedback...
    Visit pyrocat-hd.com for the suggested development times.
    16 minutes could be too much, depending on agitation. The negative should look "thin".
    TMX is a great film.
    You should look at the pyro developers/negatives as a "variable contrast developer/negative". Scan them in color and pick the channel closest to the target contrast.

  8. #38
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    Re: Pyrocat Tests and Some Disappointment?

    Quote Originally Posted by rdenney View Post
    And I thank Ken Lee for filling in that blank left in Sandy's article on the Unblinking Eye.

    Particularly: The meaning of contrast index, in terms of normal values, for people who did not read the BTZS book before reading the article on Pyrocat.
    The graphs on page 1 and 3 of the article, are different: they show Exposure on the X-axis (horizontal), and Density on the Y-axis (vertical). It's interesting to see that the stain density follows the visual density, only it's steeper - and given that UV-sensitive processes need steeper (contrastier) negatives than Silver, the prints we make on either media will have similar appearance, with no need for correction. As Dakotah rightly points out, it's all about the prints.
    Last edited by Ken Lee; 26-Mar-2012 at 15:58.

  9. #39

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    Re: Pyrocat Tests and Some Disappointment?

    Quote Originally Posted by Ken Lee View Post
    The graphs on page 1 and 3 of the article, are different: they show Exposure on the Y-axis (horizontal), and Density on the X-axis (vertical). It's interesting to see that the stain density follows the visual density, only it's steeper - and given that UV-sensitive processes need steeper (contrastier) negatives than Silver, the prints we make on either media will have similar appearance, with no need for correction. As Dakotah rightly points out, it's all about the prints.
    Yes, the dual purpose character of pyro stained developers is a real plus for photographers who print with their in-camera negatives in both silver and pt/pd (and other UV sensitive processes). This has been known for a long time. Edward Weston comments on it in one of his day books, as I recall with reference to a negative he made while in Mexico.

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    Re: Pyrocat Tests and Some Disappointment?

    Quote Originally Posted by onnect17 View Post
    Some feedback...
    Visit pyrocat-hd.com for the suggested development times.
    16 minutes could be too much, depending on agitation. The negative should look "thin".
    TMX is a great film.
    You should look at the pyro developers/negatives as a "variable contrast developer/negative". Scan them in color and pick the channel closest to the target contrast.
    I think this is probably related to my issue. I'm too used to looking for 'thick' negatives, which especially given that I am restricted to scanning for the time being, is a habit worth breaking, as is eye-balling it. I haven't any time for more testing since I posted, but I have been reading and glad this sparked an informative (for me) discussion. Particularly thankful to Ken for the very thorough posts, thanks for taking the time. And Sandy thank you for chiming in, hope you don't take any of this as a slight on your work... Hopefully I'll have some new negatives in the next day or four to at least comment on in lieu of doing some more rigorous testing.

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