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  1. #1
    noseoil's Avatar
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    24 x 24 copy camera as enlarger

    I'm wondering what type of illumination might be necessary (for graded papers) to turn a 24 x 24 copy camera into a horizontal enlarger. Which bulb type would work best, fluorescent, incandescent, etc? How much output would it take to project 8x10 films onto the projection surface for large prints? What is the best way to provide even illumination to the film plane for projection? Has anyone done this on the forum?

    I've seen the Adams darkroom with 8x10 horizontal enlarger. It looked pretty basic, nothing fancy. It seems that an old copy camera might be just the thing for this type of work. Anyone have some ideas on this one? Thanks in advance, tim

  2. #2

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    Tim,

    I have been thinking of adapting copy cameras for enlarging too.

    Since there are no condensers for a 24X24 enlarger, to my knowledge, that leaves a diffusion light source. That could be accomplished in several ways. The easiest way would to build a light head using fluorescent lamps as one method that comes to mind. The problem with this is that the lamp output is relatively low as far as enlargers go. In fact I am not even sure that a bank of fluorescents would be up to the task.

    A typical 8X10 enlarger will use 1000 watts minimum with 2000 watts not being uncommon. When encountering lamps in this wattage the primary lamps that have instant on capability are halogens. This would require a mixing box to even the light out with diffusion at the light path exit onto the negative. A reflector of some design would be required to create a larger effective light source.

    If a shutter were incorporated then any number of lamps could be used since instant on would not be required.

    Fan cooling would be required.

    All in all it is worth the effort if one is wanting a LF or ULF enlarger. If I were doing this, I would build the beast to enlarge 12X20 negs and advertise the service to people who wanted really nice big prints. If I were building this type of capability then I would opt for about 4000 watts of halogen...(four lamps of 1000 watts each) I would project these into a ceramic mixing chamber and plan on about 300 CFM of induction cooling.


    I wonder if roll paper comes in 48 inch widths?

  3. #3
    glbeas's Avatar
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    Some of the more advanced copy cameras have a backlit copyboard, eg diffusion illumination, for copying slides and other transparencies. This makes it possible to make prints of large negs using the copy camera without any modification, just set it up for transparency copies. Some have a flourescent unit under the regular copyboard and you just need to take off the covering and turn on the lighting, others may have to have the lights swung around to the back of the copyboard to work.
    Gary Beasley

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    I would consider a cold light source. I have the Aristo T-12, which is a 12x12 unit which has a V-54 tube and is rated at 320 watts, and it is more than adequate for 8x10. Aristo also makes a T-28, which is a 24x28 inch model with 1070 watts, and a T-36, which is a 32x36 inch model with 2140 watts. I’ve talked to the engineer at Aristo, and as I understand it, Aristo can bend up a V-54 tube for these, and possibly supply a higher voltage transformer to even more light output.
    —Eric

  5. #5
    Mick Fagan's Avatar
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    Donald, roll paper used to come in 6' widths for colour negative, from Kodak.

    B&W Ilford multigrade was produced to 4' wide and their RT machines were 4'3" wide (I think).

    I'm not sure whether you will find the same roll paper today, but transporting was a problem, especially if it travelled overseas. The containers for the paper looked like small lead coffins and cost a packet.

    As for a shutter requirement for an enlarger that can cover 10x10" I have used shuttered and shutterless enlargers.

    All of the shutterless 10x10" enlargers seemed to have the same type of output; two banks of 4 x 250W enlarging globes for a given output of 2,000W. The downside if you are enlarging colour, is that if a globe blows, then you have to change all 8 globes.

    With B&W you can sort of get away with replacing the blown globe, but you then end up with uneven illumination, personal experience here!

    I think AA's enlarger had 36 light globes for extreme illumination consistency.

    One thing most copy cameras have is a light sensor stabiliser. This measures the amount of light given and turns off the lights when the required level of light has been received. Adapting one of these sensor units to a copy camera enlarger would virtually alleviate a shutter requirement and/or a timer.

    Mick.

  6. #6
    noseoil's Avatar
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    Everyone, thanks for the input so far. What prompted this thought was a 24 X 24 X 16' copy camera I have access to, which needs a new home. ("Gee honey, can I keep it? It followed me home while I was out walking and...")

    I'm thinking that a Packard shutter would certainly work to use as a bass-ackwards shutter for enlarging, since most times will be in the neighborhood of seconds, it isn't too critical, as with film exposure. A metronome would work for timing or a Graylab 300 hooked to a relay would probably suffice.

    There still remains the light source. 4KW of output is a bit on the hot side, so Donald I'll take your measurement as a starting point of 300 cfm. This means a clean air supply and open air flow to dump the heat. Might have to rework the family clothes drier to cut down on energy costs and use the "free heat" for something other than global warming. Could get a few complaints from neighbors when lights dim in the area, but would blame that one on the power company's voltage fluctuations. If a shutter works out well enough, incandescent flood lamps in a bank might provide enough light output to stay away from exotics and transformers.

    A ceramic mixing chamber... Have to do a bit of research on that one to see what is an inexpensive design using surplus materials. Anyone point me in that direction? Will have a look for someting I can copy and adapt on google. There might be some interest in this type of setup for visitors from "other areas" like someone from "Area 51" perhaps, who could visit for a printing session.Still brainstorming on this one, but the idea seems pretty sound as far as the chassis and basic enlarger. tim

  7. #7

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    You might consider white ceramic tiles inside of a mdf (or steel?) box.. You could cut the tiles with a tile cutter to fit. That would be the easiest way to have a ceramic light mixing box that I could think of..

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    Tim,

    The Packard would work as a shutter if you remove the pneumatic actuator and replace it with a small electrical solonoid. A spring return would need to be incorporated into the actuator redesign. WW Grainger should have what you need in the way of an actuator.

    My recommendations of wattage were based on a 12X20 enlarger. I would cut that down for an 8X10.

    But think of it this way, how many people have a 12X20 enlarger? I can think of only two. Clyde Butcher in Florida and a fellow in Chicago. So there may be someone who wants to make really good sized 12X20 enlargements.

    This of course would need to be run on 230 volt 60 hz to power the lamps for amperage considerations. 4,000 watts would still consume 17.50 amps and that is a sizeable demand. It may be possible to design this in a stepped increase so that the 4,000 watts would only be used with the larger negatives.

    Heat here in Az is a consideration. You could always convert your enlarger into a tanning salon during the off season. Set it up in such a way that you incorporate a mirror to toast them on both sides at once. It would be a source of revenue that you might use to convince your wife of the legitimacy of your reasoning.

    Clothes drying would be a nice use...I doubt that your small family would dirty enough clothes however...maybe you could set up a neighborhood laundromat.

    This could be the single greatest thing to happen in your life, Tim.

    I can see it now...television infomercials touting your path to riches.

  9. #9
    rbarker's Avatar
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    Another thought would be to adapt one of Arri's 12,000 watt Arrisun lights. They have a front opening of around 20", and incorporate their own cooling fan. The downside would be having to place it in the next room (with dedicated A/C). And, there might be a need for some heat-absorbing glass between it and the negative.
    [COLOR=SlateGray]"You can't depend on your eyes if your imagination is out of focus." -Mark Twain[/COLOR]

    Ralph Barker
    Rio Rancho, NM

  10. #10

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    Tim

    if you check this link on my website you'll see a converted 16x20 enlarger, not quite as big as yours but may give you some ideas.

    http://www.bigshotz.co.nz/mike_westmoreland.html

    Clayton

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