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  1. #1

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    Sun as a UV source

    Hi all...

    Gathering info before getting started in alt processes and had a simple question. When using the sun as your UV source (pretty dependable here in So Cal) should the printng frame be out in direct sunlight facing the sun, or in open shade facing the sky?

    I remember reading something about different contrast results in particular locations (full sun, open shade, etc...) so I'd like to know what y'all suggest.

    I'll probably be starting with an Argyrotype process...

  2. #2
    dpurdy's Avatar
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    I have always aimed the print directly as possible at the sun. I love sun printing. I did read that you get a boost in contrast by printing in shade.

  3. #3

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    I've tried both for cyanotype and apart from the difference in exposure time see no convincing difference. However cyanos usually take (me) about 10' in direct sun and self mask to an extent so over-exposure is not a massive deal. From what I gather argyrotypes need pretty standard exposures (http://www.alternativephotography.co...rgyrotype.html).
    You might also want to look at http://www.alternativephotography.co...es/art068.html which is a summary of responses to questions about cyano printing. This leads me to the conclusion that it doesnt much matter which way you go, but that you need to get a consistent method that works for you.
    As always with alt-process go forth and experiment my child!

  4. #4

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    Pasadena, eh? I was born at Huntington, and still live nearby. Let me know if you need to borrow any of my alt. process stuff. Not much fancy - just a few brushes, some chemicals, and a 20x24 Formulary printing frame. I also have the Christopher James Alt. Processes book, which you are welcome to borrow. I also have some VDB mixed, although It is about 6 months old now.
    Last edited by 2F/2F; 09-23-2008 at 09:57 PM. Click to view previous post history.
    2F/2F

    "Truth and love are my law and worship. Form and conscience are my manifestation and guide. Nature and peace are my shelter and companions. Order is my attitude. Beauty and perfection are my attack."

    - Rob Tyner (1944 - 1991)

  5. #5
    Vaughn's Avatar
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    I have read recommendations for Salt prints to start in the sun and finish in the shade (or was it the other way around? or was that for cyanotypes?) Anyway, the idea is that the tonality of the final print changes for the better if the sun-stuck chemicals in the paper have some time to go all the way through their reactions...short intense exposures appearently do not allow for this. Terry King of Great Britian (and historian for the Royal Photograhic Society) has suggested the same thing for platinum printing.

    I believe Christopher James mentions it also in his second edition.

    Vaughn
    At least with LF landscape, a bad day of photography can still be a good day of exercise.

  6. #6
    David A. Goldfarb's Avatar
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    For albumen the traditional sources say that one gets higher contrast with indirect light, and it seems to be true, but in my experience it is very subtle. It may have to do with how long the overall exposure time is--maybe after a certain length of time, it doesn't make a big difference, but for thinner negs with a short exposure time, maybe it makes a bigger difference. My best albumen negs print 20 minutes in direct light, 1 hour in indirect light, which is long, but it works for me.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
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  7. #7

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    Quote Originally Posted by David A. Goldfarb View Post
    For It may have to do with how long the overall exposure time is--maybe after a certain length of time, it doesn't make a big difference, but for thinner negs with a short exposure time, maybe it makes a bigger difference.
    Reciprocity failure being induced with the longer, shade exposures?

  8. #8

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    For salt prints I understand that northern light is best, not direct sun, but it depends on the neg. also, density, etc.

  9. #9
    David A. Goldfarb's Avatar
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    Quote Originally Posted by Kirk Keyes View Post
    Reciprocity failure being induced with the longer, shade exposures?
    I'm not sure. I don't think it's reciprocity failure, because the difference between direct sun through a window and shade is about two stops, and the time difference is also two stops. It may be the reaction time issue that Vaughn mentions.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
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  10. #10

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    I'm dubious of "reaction time". It should be a very fast chemical reaction.

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