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Thread: f64

  1. #71

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    Re: f64

    Quote Originally Posted by Ken Lee View Post
    Perhaps you were referring to Pyrocatechin alone.
    Ken,
    I used to use PMK all the time... back when I was doing trays. I used PyroCat a couple of years ago and failed miserably with it. However, I hasten to add, it was totally my fault... I'm going to try it again...

    Lenny

  2. #72

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    Re: f64

    Quote Originally Posted by Lenny Eiger View Post

    When looking at onnect17's example, a couple of things that come to mind. Mainly, his Xtol was simply more active than the Pyro. This means that it went thru like a roto-rooter. It washed out silver between the grains. It also did not articulate the darker areas as well.

    Lenny
    You would want to always compare developers with a given film at the same contrast. Frankly the two samples look pretty close to me in contrast, though one would have to measure the original negatives to be sure.

    But I am fascinated by your comment, "it went thru like a roto-rooter. It washed out silver between the grains? " I am having a real problem getting my mind around how a developer washes out silver! The action of developers is such that they reduce various forms of silver salts to silver metal. I don't believe there is any mechanism by which a developer washes out silver. If a developer is more energetic it simply performs the action of reduction faster but there is no roto-rooter action going on.

    Sandy
    http://www.sandykingphotography.com/
    For discussion and information about carbon transfer please visit the carbon group at Yahoo.
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  3. #73

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    Re: f64

    Quote Originally Posted by sanking View Post
    But I am fascinated by your comment, "it went thru like a roto-rooter.
    Sandy, This comment is relative to what I think I understand about the process at a molecular level. What was explained to me many years ago (and from my reading the the Photochemistry book) is that during exposure the photons affect only a few molecules at the top of the emulsion, and that the developer that comes after drills down into the emulsion following the tracing of the those affected molecules. It was explained in fairly dramatic terms. Roto-rooter came to mind. When things are considerably more active, this redox reaction is more intense and there are different effects caused by this change.

    Now, of course, that was a long time ago. They could have re-written the books entirely based on better information and I could be all wrong... that's why I said its what I think I understand...

    Quote Originally Posted by sanking View Post
    It washed out silver between the grains? " I am having a real problem getting my mind around how a developer washes out silver! The action of developers is such that they reduce various forms of silver salts to silver metal. I don't believe there is any mechanism by which a developer washes out silver.
    In that instance, I was speaking about developers vs developing agents. Some developers which have a lot of sodium sulfite, for instance, wash out spaces between the grains, or wash off the edges of the grains so that the grains are smaller. They are called solvent-type developers because of this. Looking at the grains in question, it appeared that the developer used has some sort of mild solvent action going on. I suppose it could also be something else.

    I don't pretend to be a chemist... I was trying to answer a question, and not to be the authority on this subject (which I am not). Clarification is welcome.

    Lenny

  4. #74

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    Re: f64

    Lenny,

    There is no question but that the latent image that is formed during exposure must be amplified many thousands of times during development to form a strong visible image. I have no problem with that idea if that is what you mean by "roto-rooter." However, I don't find anything in the literature about silver being washed away. This simply does not happen, at least by any understanding I have of the development process.

    However, I don't think any of this has anything to do with why pyro developers produce sharper negatives. That is due primarily, IMO, to the fact that pyro developers tan the image site and this results in a more precise reduction because there is very little migration of development outside of the image site.

    Several years ago I compared several pyro staining and tanning developers with several traditional non staining developers. In every case the pyro developers produced better resolution by about 15% to 20% compared to the traditional developers. The issue is that you have to go to a fairly high magnification to appreciate the difference.

    Sandy
    http://www.sandykingphotography.com/
    For discussion and information about carbon transfer please visit the carbon group at Yahoo.
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  5. #75
    A.K.A Lucky Bloke ;-)
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    Re: f64

    Lenny,

    Just to clarify some points.
    I used xtol stock solution. According to Kodak it produces the smallest grain.
    510-pyro contains ascorbic acid and phenidone and the results were very close to the pyrocat-hd.
    You can accommodate your preferences regarding the time spent in front of the jobo. Either 22 minutes, 1hour, or the 10 minutes I used here.

    The reason I use 35mm for the tests is simple. I expose a roll under the same conditions so I can use cuts to compare different developers. It’s quick, cheap and fast to scan.

    As a format, 35mm is as good as any other. The only thing missing is the ground glass

    I use 4x5 for the flatness of the film and when I want over 300 dpi in 44” paper. It’s cheaper that 8x10, more emulsions available and produces similar information at 4000dpi than a 8x10 at 2000dpi.

    Allow me to suggest to stay with xtol if you are happy with the results and even try f/128. After all that was the reason you started the thread.

  6. #76
    A.K.A Lucky Bloke ;-)
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    Re: f64

    Quote Originally Posted by sanking View Post
    Several years ago I compared several pyro staining and tanning developers with several traditional non staining developers. In every case the pyro developers produced better resolution by about 15% to 20% compared to the traditional developers. The issue is that you have to go to a fairly high magnification to appreciate the difference.

    Sandy
    Hi Sandy,
    If you have any notes about it you should write an article. The subject is very interesting.

  7. #77

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    Re: f64

    Quote Originally Posted by onnect17 View Post
    Lenny,

    Just to clarify some points.
    I used xtol stock solution. According to Kodak it produces the smallest grain.
    I would be interested if this were true. It runs counter to what I think I understand.... it would seem a bit strong at full concentration.

    Quote Originally Posted by onnect17 View Post
    I use 4x5 for the flatness of the film and when I want over 300 dpi in 44 paper. Its cheaper that 8x10, more emulsions available and produces similar information at 4000dpi than a 8x10 at 2000dpi.
    This point I would disagree with. I racked my brain over this for years. Some part of me was insistent that "it should work" and yet the prints are strikingly different. Film real estate is a huge factor in textural reproduction. However, before anyone responds, let me finish my test... this is what its really about... what can 4x5 and 6x7 actually do...

    Lenny

  8. #78
    Drew Wiley
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    Re: f64

    Lenny - you should email Joseph Holmes over in my neighborhood. He's looked at this kind up question rightside-up, upside-down and sideways, and is as nitpicky with
    film and lenses as I am, but also extremely knowledgeable with large format digital
    output. Just because I personally have a traditional darkroom bias doesn't mean that
    I haven't had fascinating discussions with these kinds of guys about the options.

  9. #79

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    Re: f64

    Quote Originally Posted by Drew Wiley View Post
    Lenny - you should email Joseph Holmes over in my neighborhood. He's looked at this kind up question rightside-up, upside-down and sideways, and is as nitpicky with
    film and lenses as I am, but also extremely knowledgeable with large format digital
    output. Just because I personally have a traditional darkroom bias doesn't mean that
    I haven't had fascinating discussions with these kinds of guys about the options.
    I've spent time talking to Joe. Nice guy.

    Of course, he is after a very different result than I am... I don't actually need Joe's help in this. I am also extremely knowledgeable with digital output. I have two 12 color printers, one for color and one for b&w.

    Lenny

  10. #80
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    Re: f64

    Quote Originally Posted by Lenny Eiger View Post
    I would be interested if this were true. It runs counter to what I think I understand.... it would seem a bit strong at full concentration.
    In publication J-109 titled "KODAK PROFESSIONAL XTOL
    Developer", page 2, second column, 3rd paragraph, it reads:

    Dilution at 1:1 will provide slightly greater film speed,
    enhanced sharpness and shadow detail, and slightly more
    grain
    .


    You can access the publication here:
    http://www.largeformatphotography.in...reply&p=678173

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