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  1. #41
    Bill Burk's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    It could have been a form of bromide/iodide drag or transfer. But those negatives must have been in close contact!

    PE
    They were. One pair out of a stack of 6 or 7 sheets, were emulsion to emulsion because I flipped one sheet over. Sure I shuffled the sheets, but the pair stayed together the entire time in developer.

    Could have been bromide/iodide... Is that what Todd-Zakia mean by "reaction products"?

  2. #42

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    Like a quasi-diffusion transfer .

    There are all sorts of reaction products depending on the emulsion and developer constituents, but bromides are fairly typical. Iodide can be there too.

    PE: How do you plan on testing your HA dev along the way? What methods will you use? I'm assuming for example you don't have a microdensitometer handy - unless you've been holding out on us!! Also if there is any way I can help you with this project let me know.

    By the way, following my mention of the reference to a patent of yours in Haist I wanted to provide more detail for anyone interested. It is on page 467 of volume II in the Color Photographic Systems chapter, The Nature of Color Development section, Color Developing Agents subsection. "In a 1972 patent Richard L. Bent and Rowland G. Mowrey claimed certain p-phenylenediamine derivatives produced image dyes of superior stability to prolonged exposure to light, heat, or humidity. ...". The reference indicates "Color Photographic Processes," U.S. Pat. 3,656,950 (1972).

    I quick question for everyone/anyone regarding copyright etc. If I reference Richard Henry clearly am I allowed to scan and post say a table of results from his book in this thread? Sorry if that is a dumb question but I have no idea what we're allowed and not allowed to do and we all remember that recent insane thread (now deleted) with the guy who was trying to make a formula book.
    Last edited by Michael R 1974; 06-20-2013 at 07:58 PM. Click to view previous post history.

  3. #43
    Bill Burk's Avatar
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    My main point is that stack developing in trays might surprise you with edge effects that you don't get in rotary or tank processing...

    I think a diagram and discussion of what it means would be appropriate, but a page copied outright is less appropriate.

  4. #44
    Photo Engineer's Avatar
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    The references in my book are all made with permission of the original authors. For example, I talked personally to Grant Haist and Bruce Kahn and got their approval. In fact, Bruce gave me a CD with his entire outline for his GEH course.

    The reference is to CD6. I had forgotten that Grant referenced that. It was planned for RA4 but missed the boat. It was used for Kodachrome.

    I will be testing my HA developer with a set of evaporated metal high definition negative and positive images that cost about $500! And a friend of mine has build a micro densitometer! No problem with testing!

    So, there you are!

    PE

  5. #45

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    What are your guiding principles in designing the developer? In other words what are you trying for when you say HA? Low solvent action? Maximum edge effects? What characteristics or components of image definition/information are you favouring? How will R G Mowrey determine if he is successful in generating "high acutance"?

    Is Holmburgers helping you with this?

    And how do I get access to this microdensitometer

    For the Henry tests I will put together a summary rather than lifting a page via scan.

    I'm also attaching my summary of the Altman/Henn study again (was discussed in another thread some months ago).
    Attached Files

  6. #46
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    Michael;

    My benchmarks will be a family of films tested aganst HC110 and D76. The film will have to have the same contrast and speed in the HA developer with better grain and sharpness. We will see what we will see. And no, Chris is not working with me on this. Our work is strictly emulsion work. I'm working with others on this.

    I do not have use of the microdensitometer, I just know he has one. I have yet to ask for its use.

    PE

  7. #47
    Bill Burk's Avatar
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    Could a scanner be used for a microdensitometer? I have used a scanner for a densitometer before... seems at a modest scale it could be useful.

  8. #48
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    Yes Bill, it can. I believe that there is another thread on this.

    However, the data then becomes a square wave instead of a sine wave of noise which represents the grain. IDK if that is what I really want. Kriss discusses this and I have to do more studying and bone up on my Calculus and DE.

    PE

  9. #49

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    PE, do the sharpness aspects of Kriss's image content model relate to MTF in any way?
    Last edited by Michael R 1974; 06-24-2013 at 03:40 PM. Click to view previous post history. Reason: Clarity

  10. #50

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    Quote Originally Posted by Alan Johnson View Post
    I did investigate the difference between 3-min agitation intervals and stand development:
    http://www.apug.org/forums/forum37/5...velopment.html
    Nowadays I use Don Cardwell's recommendation from his reply.
    Alan, for some reason I missed this earlier. Very interesting test. Just to clarify re Henry's tests, when there was pre-exposure he did find statistically significant fringe effects even with D-76. With no pre-exposure perhaps the problem is that he did not investigate longer agitation intervals than 1 minute, while your test started with 3 minute intervals. Or it may be he did not find any statistically significant edge effects. It also may be there is more density in the low density side of your negative than you thought. I think it makes some sense to expect a fringe effect of some kind even at base fog, but it would likely be very small so who knows.

    Henry used a variety of developers including Beutler and Rodinal and refers to these tests on p. 226. In fact his Rodinal tests were quite interesting. The developer produced more pronounced edge effects and higher granularity than D-76 1:1 with Pan-X and Tri-X, but not higher acutance.



 

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