Using a Variac to lower condenser heat generation?

Would it be possible to use a Variac to lower the condenser bulb voltage, so that less heat is generated in the upper stage of condenser enlarger?

jay moussy said:

Would it be possible to use a Variac to lower the condenser bulb voltage, so that less heat is generated in the upper stage of condenser enlarger?

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Lowering the voltage will also cause less light to be generated, resulting in longer exposure times with more time for heat to build up - my guess is that at best, you will break even. You could possibly test this, however, with a cheap dimmer switch before investing in a Variac. Full disclosure: I'm not a physicist or an electrician, so please don't electrocute yourself following my strictly theoretical, don't-try-this-at-home non-advice!

EDIT: if you are routinely having to stop your enlarger lens way down, or even having to use ND filters to get reasonable times, then this might make sense.

PFGS said:

Lowering the voltage will also cause less light to be generated

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Not only lesser light is emmitted, but also the spectral characteristic changes, it gets even more reddish. Meaning a further reduction in effectivity.

AgX said:

Not only lesser light is emmitted, but also the spectral characteristic changes, it gets even more reddish. Meaning a further reduction in effectivity.

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Exactly. Problems will result for both b&w work as well as color.

Best just fit in a lower power bulb of the right voltage or, if you're adventurous, convert to led.

What about dimming LED's ?

You could try using heat absorbing glass in the filter drawer.

AgX said:

What about dimming LED's ?

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Works, especially if pwm is used.

AgX said:

What about dimming LED's ?

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It would hard for me to pick the right one with regards to spectrum, start-up time/after-glow issues.
Why wouldn't the usual supply houses carry qualified enlarger-compatible LED bulbs?