UV for enlarger

Discussion in 'Darkroom Equipment' started by PhotographyStudent98, Feb 7, 2018.

  1. PhotographyStudent98

    PhotographyStudent98 Member

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    HELP!
    I've bought sunprint paper for a college project which only works with UV rays. The thing is I don't want it to look boring by just putting an object on the paper and leaving it in the sun so what I was wondering was if there was any way I could use the sunprint paper in the darkroom? Like is there some sort of Equipement i could buy for an enlarger to make it uv light instead of white light?
    Thanks!
     
  2. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    Problems with that concept are how to focus and UV absorption by the enlarging lens.

    The usual method for enlarging for UV processes is make a bigger negative, either by copying a print with a larger camera or making an interpositive, and then an enlarged negative with an enlarger, usually using ortho film, or scanning the negative and printing on a transparent medium, and then contact printing the enlarged negative.

    There are threads here on both approaches. You can use the search engine to find threads on conventionally enlarged negatives, and there is a subforum in the Hybrid section of Photrio for discussion of digitally enlarged negatives.
     
  3. Svenedin

    Svenedin Subscriber

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    You can buy UV lamps that would be suitable to contact print a negative onto your sun print paper but this is of course a 1:1 enlargement and you would need to be able to make a big enough negative. I'm not aware of any suitable UV light source to use in a conventional enlarger. Be aware that some UV light sources are potentially hazardous to eyes and skin. If you want to go down the contact printing route then you can make your enlarged negative using a hybrid route (scan the negative and print larger onto permajet negative transfer film) or the traditional way via an interpositive.
     
  4. OP
    OP
    PhotographyStudent98

    PhotographyStudent98 Member

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    Great! Thank you both
     
  5. darkroommike

    darkroommike Subscriber

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    You can make LF negatives with a digital printer then contact print them on the Sunprint paper. I have used both paper and transparency material to do this.
     
  6. stormpetrel

    stormpetrel Subscriber

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    If you plan to enlarge with a UV light source, use nikkor lenses as they have a wider transmission spectrum. They start at 380nm. Schneider/Rodenstock enlarger lenses start at > 400nm.
     
  7. NedL

    NedL Subscriber

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    That's interesting! How close do you think the focus would be if you focused using a blue filter? Close enough to get there by stopping down a few stops?
    I wonder which processes would work at 380nm.... hmmm....

    Edit: according to this, it might work better for kallitype, vdb or pd/pt, and not as well for cyanotype or dichromate-based processes like carbon and gum.
     
    Last edited: Feb 9, 2018
  8. wyofilm

    wyofilm Subscriber

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    I always imagined the biggest problem with enlarging with a UV light source would be absorption. I supposed that with a little trial and a good bit of error it would be possible to focus with visible spectrum light then move the lens a pre-determined amount. Also, stop down the lens as NedL suggests. I didn't know the nikkor lenses would pass UV down to 380nm. Interesting.
     
  9. stormpetrel

    stormpetrel Subscriber

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    I made a multigrade led for my durst 139 with uv and green leds. I thought I would have a better control on the grade but it was a mistake as multigrade papers are too sensitive in the uv. Now I use blue leds instead. I have not tested my uv head for alternative process yet but I m quite confident it could do a good job especially considering the number of uv led i have used (far too many)....I could clearly see the difference between nikkor lenses and other brands (confirmed by manufacturer datasheets). I have posted some details about this multigrade diy head on apug a long time ago but i could find the thread back if you are interested. Prepare your safety uv glasses....
     
  10. stormpetrel

    stormpetrel Subscriber

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    I have two other color channels on my DIY multigrade head cyan and red. I use cyan for focusing (half way between blue and green).Blue or UV leds, the pictures come perfectly sharp. I did not want to focus with the grain focuser under UV light this why i added the cyan channel.
     
  11. NedL

    NedL Subscriber

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    That answers it. Thanks!
     
  12. wyofilm

    wyofilm Subscriber

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    Fantastic!
     
  13. Vaughn

    Vaughn Subscriber

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    Pinhole cameras are another fun/nice way to produce negs big enough for cyanotypes.
    Going a hybrid path (inkjet negs) would be the quickest way for larger negatives...and makes the project free from additional chemicals.
    But speaking of additional chemicals, you might want to search toning of cyanotypes -- many chemicals needed are household items.

    Have fun!
     
  14. RalphLambrecht

    RalphLambrecht Subscriber

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    replacing the enlarging lens with a pinhole would work.
     
  15. nmp

    nmp Member

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    Stick with boring. This article does a nice job explaining why. Besides, who said it looks boring to expose the paper in the sun?

    http://www.co-mag.net/2007/uv-printing-unit-enlarger/
     
  16. CMoore

    CMoore Subscriber

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    I am lost.
    Why would UV Light from Natures Sun look "boring", and UV Light from a plug-in device look "better" or not "boring".?
    Does the sun light do something bad to those types of paper.?
    Thank You
     
  17. NedL

    NedL Subscriber

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    :D I think OP doesn't want to make a photogram and doesn't have any big negatives.
    But I'm with you... it's not boring to expose a print in the sun. Just about my favorite thing to do!
     
  18. OP
    OP
    PhotographyStudent98

    PhotographyStudent98 Member

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    No no nothing like that but from what ive seen of sun print paper you leave it in the sun with an object on the top and i want to try something different than just a flower or a leaf i want to try and do a proper print on the paper
     
  19. CMoore

    CMoore Subscriber

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    .....it is not different than using a UV machine.
    So put whatever you want on The INSIDE of the contact printer and leave That in the sun......just like you would do with man-made sun.:wondering:
     
  20. OP
    OP
    PhotographyStudent98

    PhotographyStudent98 Member

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    boring was maybe the wrong word - i want to try something different, everything i have seen has been plant based but i want to make it into an actual print like from a negative
     
  21. jim10219

    jim10219 Member

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    When I first started out doing cyanotypes and gum bichromates, I went to my local copy shop (Kinko’s or Staples here in the US) and had them print negatives on transparency paper. They cost me about $1 a piece and we’re reusable. Then, just lay a piece of glass over the negative and paper, expose in the sun, and wash in the tub. Cheap and easy!

    Using an enlarger would be exceedingly difficult. You’d have to fight with negatives warping from the heat of such long exposures and all kinds of expensive modifications to get the right light.
     
  22. Svenedin

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  23. Svenedin

    Svenedin Subscriber

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