4x5 contacts - basic light source?

Discussion in 'Contact Printing' started by dr__red, Dec 19, 2005.

  1. dr__red

    dr__red Member

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    I'm working on my first setup that will hopefully allow me to do 4x5 contacts. I'll keep it down to basics: darkness, frame, few trays and Adox or Ilford of some sort (not ready to splash on Azo just yet). My bold guess would be I'll also need a Bulb. But what kind of and how far above the frame? The basic exposure guideline to start with would be much appreciated (20sec?). I'm total newbie in this stuff (currently in transition from digital to chemical) so your patience is much appreciated. Hack I developed my first 4x5 in tray full of pyrocat just last week!
     
  2. TheFlyingCamera

    TheFlyingCamera Membership Council Council

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    Basic exposure will vary so much by the distance you have the light source, the type and intensity of the light source, and the paper/developer combo you are using, that giving you a reasonable guess is meaningless. I do my contacts on variable contrast silver paper, using my dichro head enlarger, and I get about 30 seconds @ F22-F32 using my 135mm enlarging lens. If you were to use a bare bulb, you would probably get much shorter exposure times unless you use a low wattage bulb a fair distance from the paper. It may not make as much a difference with contact printing, but when using an enlarger, make sure that your bulb is a frosted, diffused lightbulb so you don't get the apparent pattern of the filament showing up in your image.


     
  3. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    If you don't have an enlarger, and you're not using Azo, then your exposure time is going to be very short and possibly hard to control. I'd use something like a 15 watt bulb at least a few feet from the paper to start with.
     
  4. MattCarey

    MattCarey Member

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    I did some of this using the light bulb over my bathtub (not a very bright bulb, but neither am I!).

    The times were too short to control. I taped a piece of paper over the light bulb and got better results. This was with graded paper so I didn't worry about the contrast shifting (I believe the paper would give a more red color).

    Matt
     
  5. John Bartley

    John Bartley Member

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    Before I had an enlarger and before I knew about AZO, I did a few 4x5 contacts on Ilford MGRC paper. I used a 7 watt refrigerator bulb in a desktop lamp about 36" above the frame and filtered it through a light blue (as close to magenta as I could find) plastic sheet cut from a kids school report cover. With this setup I was able to stretch the exposure times to as much as 30-45 seconds, even with this fast paper.

    cheers
     
  6. Donald Qualls

    Donald Qualls Member

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    I've heard of 7W or 15W bulbs installed in coffee cans with an aperture at the open end of the can to control how much light escapes; this is then suspended at a known, repeatable distance above the contact printing frame/easel/counter. The shiny metal interior of the can will tend to cast a reasonably even light over a pretty well defined circle, and the low wattage and small aperture keep the times from being uncomfortably short (start with a hole an inch in diameter and adjust if your times are too long or too short for convenience; you can also change wattage if needed).

    Ideally, you'd want a heavily frosted bulb with no printing on the end opposite the threads, but for contact printing without a condenser it probably doesn't make much if any difference.
     
  7. dr__red

    dr__red Member

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    Hmm... Now I'm thinking it might be a Good Idea (C) to use transparency viewer's cold cathode light panel to make an exposure. It is very uniform, not very bright - just might be a ticket. What do you think fellows?
     
  8. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    It would be easy enough to test, and if it's too bright, just put sheets of paper over it to reduce output.
     
  9. seadrive

    seadrive Member

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    Take a look at this thread:

    http://www.apug.org/forums/showthread.php?t=19519

    and the attached picture. It's a 30w flood.

    The bullet reflector is 6" in diameter, and it's about 28" above the contact printer. If you tape a couple of sheets of tracing paper (or other translucent material) over the reflector, you can get exposures in the 15-20 second range.

    Of course, it depends on the speed of the paper you're using. I've been using some Ilford Galerie, which is pretty fast.

    Hope this helps.

    Steve
     

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  10. dr__red

    dr__red Member

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    Just saw the pix of your darkroom. Bravo! I am in somewhat worse situation since my washing machine I happened to reuse for darkroom purpose is also a cutting edge device which combines washer and dryer in one piece effectively halving darkroom workspace... What was I thinking 3 years ago while buying it?? Trues though I was still stuck with 35mm E6 scanning at that very time...
     
  11. mikepry

    mikepry Subscriber

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    I did a fairly large project concact printing onto Fortezo GR 2 and I set up a 15w bulb about 4 feet over my print frame and wrapped the bulb with toilet paper and it worked great. Very good print times and the light was never on long enough to worry about heat and even then the 15w doesn't generate allot of heat. To hold the tissue on all you do is get it in place and simply wet it at a spot and it will kinda weld itself together in place. Good luck!
     
  12. jeroldharter

    jeroldharter Member

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    I use the dichroic head of my enlarger but I understand you are trying to do things more simply.

    I have never doen this, but I would think about using one of the little, bullet shaped safelights. You could add a large blue or green gel filter for split contrast printing or polycontrast filters for regular printing. The safelight bulbs are 7 or 15 watts I think and with the added density of the filter you should be able to get relatively short exposure times. You could hook it up to an enlarger timer for fairly reliable exposure times so long as they are not too short.