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  1. #11

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    Whoa! This is counterintuitive. I've recently had a renewed interest in divided developers owing to their ability to linearize the sensitometric curve at the low negative density end. This seems to clearly provide for greater discrimination of detail in the shadow region of the print. Maybe I've not grasped the suttleness of your comment above. Perhaps you are implying that the lower gamma in the tail of the sensitometric curve (the first derivative of that curve function) when taken a second time yields a steep slope and thus a greater shadow discrimination than would be intuitively expected. Interesting thought but I'm not sure I'm grasping your intent very clearly.

    Nate Potter, Austin TX.

  2. #12
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    Well, the shadow detail of a print takes place in the shoulder end of the paper curve. With lower contrast or extended scale there, you see more before total blackness takes place. So, a slightly elongated shoulder enhances shadow detail. Even though the mid scale and toe of the paper may be the same, you can see more depth in shadows if the shoulder scale is extended. This is due to the fact that paper has a limited scale due to multiple internal reflections which confounds intuition by means of physics.

    PE

  3. #13

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    There are few new non-specialist developers.One is Ilfosol 3,for which Ilford have a safety data sheet.One could guess that it leaves out ascorbate and perhaps dimezone.
    There are few photochemists left in B/W research.I believe Ilford have about 12, Kodak and Fuji numbers would be interesting to know.
    But I daresay there is less effort goes into new developer secrets than might be inferred from the last part of the quick question.

  4. #14
    Nicholas Lindan's Avatar
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    The greatest developer secret of all time: There are no developer secrets.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  5. #15
    Ian Grant's Avatar
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    Quote Originally Posted by Nicholas Lindan View Post
    The greatest developer secret of all time: There are no developer secrets.
    There are/were and unfortunately most will be lost.

    Companies like Johnson's in the UK made great developers, so did many other smaller companies now long closed.

    Kodak (UK) used to sell a High Definition developer not manufactured or imported by Eastman Kodak in the US/Canada that remains a secret but it competed with other high acutance developers like Ilford Hyfin and Johnson's Definol.

    Older developers like Rodinal took on a new lease of life with the advent films like AP100/APX100 and Tmax and experimental developers that were found to be unsuitable for old style thicker/unhardened emulsions.

    A good example is how Pro developers have made a big comeback in recent years through the work of Gordon Hutchins and Sany King

    Others are working to revive PPD - Glycin, Metol, Phenidone & Pyrocatechin combinations. This was an area Johnson's were particularly strong in.

    Ian

  6. #16

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    Quote Originally Posted by Nicholas Lindan View Post
    The greatest developer secret of all time: There are no developer secrets.
    How about Metering Secrets?

    I'd like to build a cumulative light meter...
    something that will just tell me how much exposure has been given....

    Could you suggest anything I might be able to put together myself?

    Ray

  7. #17
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    Quote Originally Posted by Nicholas Lindan View Post
    The greatest developer secret of all time: There are no developer secrets.
    I have to agree with Ian and disagree with this statement.

    There are many developer secrets never revealed by the major companies or only revealed via patents.

    Even then, the data is obscure and use arcane to the outsider. As I said before, I could teach a full workshop on just this subject alone. And, as I said before, I am not the best qualified to do so. Grant Haist and others would simply overwhelm you with information.

    PE

  8. #18

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    Quote Originally Posted by Photo Engineer View Post
    Another example is the preparation of D76 or Dektol powders in which the two main ingredient classes are separated from each other by an encapsulation technique that is quite confidential.

    PE
    Would that be to protect the developing agents from the other components in single-powder packages?

  9. #19
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    Yes, and it is the reason why you cannot really mix a partial packet of powder. The alkali is in one type of packet and the sulfite and developing agents are in another. It is kind of like having a 12 or 24 hour release medication that is a mixture of things. Except here, the release takes place in the hot water.

    PE

  10. #20

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    Quote Originally Posted by Ray Rogers View Post
    How about Metering Secrets?

    I'd like to build a cumulative light meter...
    something that will just tell me how much exposure has been given....

    Could you suggest anything I might be able to put together myself?

    Ray
    I'd like one of these too. Ray - start another thread and I'm sure Nicholas would be up for talking. I'd can see a home made one with a Aurdino-type controller, a small LCD readout, battery, and sensor. Make it incident to simplify the design.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

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