Converting to point source

Discussion in 'Darkroom Equipment' started by Paul Howell, May 29, 2008.

  1. Paul Howell

    Paul Howell Member

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    I just bought an old federal enlager 35mm to 6X9 (1939 issue) to convert to a point source. I selected the federal because it has narrow lamp housing. Any ideas concerning a small clear bulb? I have an old Durst Color head that I can canablize for it's halagon bulb. A couple of years ago I bought a Russain 35mm point source enlarger that uses a very small tungston bulb, looks like a large flash light bulb, all I had to do was get a new tranformer to step the voltage up to 220.
     
  2. RobC

    RobC Member

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    well if you look at the lamp for an L1200 varipoint, it uses this one:

    http://www2.durst.it/shop/prodliste.asp?prodcatid=4&ptitid=50

    so if you contact a local durst dealer or someone on the list who has one, then you may be able to get the code of the bilb and buy one from a usual bulb manufacturer for a lot less than durst are charging.

    I wouldn't have thought the tungsten bulb from a colour head would be a point source bulb. Way too big.

    However, an opal bulb with a sheet of metal with a hole in it, might do it although it could get a bit hot so care would be needed setting it up.
     
  3. bowzart

    bowzart Member

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    Most of the colorheads used halogen bulbs with those built in reflectors. All that I ever used did, and I printed color in custom labs for far too many years, probably used some 30 or so enlargers.

    Those bulbs won't provide point-like light. Ideally, a small bare bulb in a blackened chamber. The smaller the better. Some of the new automotive headlight bulbs might work, if you had a 12v high current power supply.
     
  4. Paul Howell

    Paul Howell Member

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  5. RobC

    RobC Member

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    Last edited by a moderator: Aug 11, 2008
  6. Paul Howell

    Paul Howell Member

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  7. RobC

    RobC Member

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    the picture shows the variopoint L1200 head. I have the cls501 colour head and not that one. But I know that head has a voltage rheostsat in it for adjusting brightness and it also has controls for adjusting x and y position of the lamp so that it is centred. I'm not sure if it has a fan in it but what you see as a fan may well be those controls.
    A 100W bulb would have less need for a fan. My CLS501 has a built in fan but it also has a 250W bulb which is required because with colour you are using two filters and also a diffusing box which stops a lot of light. With a point source you only have one filter and no mixing box and its focussing light onto the neg so it should not require as much light output.
    And temp in condenser setups can be a problem with negatives over heating and popping.
    If an L1200 works with only a 100W bulb I suspect you would be over doing it with any more than that on a 6x9 enlarger.
     
  8. RobC

    RobC Member

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    I dug my manual out and the box on the side of the variopoint head is the control unit for x and Y position of the lamp. I'm pretty sure there is no fan.
    I also have a modular 70 B+W and that uses a 100W opal bulb with no fan.
     
  9. Paul Howell

    Paul Howell Member

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    I plan to install a rheostat as well, even my cheap Russian 35 mm has a rehostat so I tone down the wattage. The Federal has a glass negative carrier, both 35 and 6X9, if this does not work I guess I will buy the lamp for the Durst and find a socket. thanks for your help.