Importance of lamp bulb type?

Discussion in 'Enlarging' started by morkolv, Mar 10, 2006.

  1. morkolv

    morkolv Member

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    Hi!

    Having recently acquired a old enlarger (Opemus iii) as light source for contact printing. also using contrast filters in the process..

    HOW much improvement does a proper opal bulb really make ?? Now I'm using a standard 75 w household bulb.. The printing on the bulb has been removed with a dagor77 lens cloth (kitchen scrub :smile: How much does the relative hight of the bulb over the condenser head matter for light evenness ??

    I will buy a proper lamp (ca 25 USD incl post vs 5USD for a household type) if required, but if not lets use the saving on film??

    Any testing which can be done ??
     
  2. Jim Jones

    Jim Jones Subscriber

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    Most household bulbs don't have adequate inside frosting to work well as an enlarging bulb. I've occasionally found exceptions. Also, an enlarging lamp burns hotter and thus is more efficient. Its higher temperature (and color) may slightly affect the use of variable contrast filters. As for the ideal height of the bulb, you can determine that best by trying it. When contact printing with an enlarger, it's a good idea to close the lens down a stop for more even illumination.
     
  3. Ronald Moravec

    Ronald Moravec Member

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    It will work if it is the same length and diameter or if you have sufficient adjustments to compensate. The condensers are designed to see a certain cone of light. If the cone is wrong, you will get light fall off in the corners.

    Acetone or fingernail polish remover gets the writing off easier.
     
  4. eumenius

    eumenius Member

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    I've been using the household opal (not frosted) bulbs all the time, and with great results. The special enlarger lamps were never made in the USSR. The most important point is to use the bulb with no visible defects un glass and opal layers, an to use onlu the power your enlarger is rated for - I thnk it's 100W for you Opemus, check it on the nameplate somewhere. If the lamp is more powerful than recomended, it may overheat and damage the bulb socket - of course, if it's not a porcelain one like in my old faithful Magnifax II :smile:

    Cheers, Zhenya
     
  5. simulatordan

    simulatordan Member

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    hello ,

    I've just be given an Opemus III enlarger which I've set up and started to used with pleasing results. It takes a pearl/opal 100w 'philips' bulb ( screw fitting ) according to the instructions from Meopta. I was worried about getting replacements but I found that 'woolworth' pearl bulbs are the same size and diameter. The writing on the top came off very easily without removing any opacity. I'm sure you will be able to find an equivalent spare. I was a bit sceptical about using the Opemus III but with some cut down multigrade filters in the draw it works a treat. Enjoy it.

    Regards Daniel
     
  6. rduraoc

    rduraoc Member

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    I've tried several different lamps of different brands in my Axomat 5a, nad all of them gave me light fall of, in one or another corner. I finally gave up and bought a enlarging lamp for 15€. Now the light is even. I guess you could be lucky, I wasn't...