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  1. #1
    Michael Slade's Avatar
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    sunlight vs. carbon arc...any difference?

    Is there any noticable difference in any of the alt. processes using the sun as the light source vs. a carbon arc or mercury vapor, or any other type of UV light source?

    Just curious....I'm making Kallitypes using the sun right now and that question popped into my head.


  2. #2

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    Quote Originally Posted by Michael Slade
    Is there any noticable difference in any of the alt. processes using the sun as the light source vs. a carbon arc or mercury vapor, or any other type of UV light source?

    Just curious....I'm making Kallitypes using the sun right now and that question popped into my head.

    Yes, there may be differences. When you use the sun as a light source you are in essence taking advantage of light from every part of the spectrum, whereas with artifical light sources you are using primarily lighty in the UV and near UV area. In many cases the particular spectrum that is used can cause subtle or even significant color changes in the image. You will quickly see this if you do some printing with salted paper.

    With kallitype, assuming you will later tone the images, there is not likely to be a lot of difference in image tone, if any. But every situation is different so don't take that to the bank.

    Sandy

  3. #3
    Michael Slade's Avatar
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    I figured you'd be the one to chime in! I still need to send you some moo-lah, carbon's are coming up.

    I am not planning to tone my Kallitypes. I do not plan to do any salted paper prints either, but who knows...

    Is there a reference guide that shows which band of UV light is optimum for a given printing process? Or...even within a given process there are different formulas, I wonder if the band of UV used for any given recipie of process can make changes?

    I am using the forumla for Kallitype from the 'Keepers of Light' book. I mixed my solution from scratch according to the recipie in the book.

    Today I am printing on Somerset paper and am getting very rich deep blacks with only 5 minutes of time in the sun during mid-day. I did not expect such short exposures with the sun as I have been using a Nu-Arc primarily up until today.

    Thanks for the insight...


    Quote Originally Posted by sanking
    Yes, there may be differences. When you use the sun as a light source you are in essence taking advantage of light from every part of the spectrum, whereas with artifical light sources you are using primarily lighty in the UV and near UV area. In many cases the particular spectrum that is used can cause subtle or even significant color changes in the image. You will quickly see this if you do some printing with salted paper.

    With kallitype, assuming you will later tone the images, there is not likely to be a lot of difference in image tone, if any. But every situation is different so don't take that to the bank.

    Sandy

  4. #4
    scootermm's Avatar
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    The article on Unblinkingeye by sandy is VERY informative and helpful
    http://unblinkingeye.com/Articles/Light/light.html

    its overloaded with very useful info and will likely cover more than you ever desired about the UV technical aspects (I cant imagine how long it took mr king to compile it, but nonetheless is a great resource)

    In regards to Sunlight versus artificial light UV sources. I did majority of my Van Dyke browns and such using the sun at first. worked wonderfully and gave short printing times.
    I now use a BLB UV bank of 48" flourescents and one of the main advantages I find is the repeatability and control. I can make test strips and know that with future prints Ill be able to limit my waste because I now have a controllable light source.
    take that for what its worth.

    plus I can print in the middle of the night if I want. which is nice.

  5. #5

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    Have to agree with Matt, the main reason I went with the UV light box (BLB bulbs too) was for 2 reasons - 1 repeatable results, and 2 - I can print at night
    It does make a difference for me, but I do Ziatypes and VanDykes so as Sandy said your results may vary.

    Why not tone your kallitypes? If I understand the process, they are much like VanDyke Brown and really will not last long at all unless you tone them...but I may be mistaken.
    Mike C

    Rambles

  6. #6
    Murray@uptowngallery's Avatar
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    One of those references probably discusses speed; I admit I skipped some lines as I read this.

    One comment on light spectrum. 'Low pressure pulsed xenon' lamps used in some process camera applications, and making their way into surplus users' hands, supposedly 'mimic' the solar spectrum. (rest deleted as wandering subject matter; for once I exercised a bit of posting self-control!)
    Murray



 

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