Using a Variac to lower condenser heat generation?

[jay moussy]

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?

 

[PFGS]

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?

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.

 

[AgX]

Lowering the voltage will also cause less light to be generated

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

 

[koraks]

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

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.

 

[AgX]

What about dimming LED's ?

 

[voceumana]

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

 

[koraks]

What about dimming LED's ?

Works, especially if pwm is used.

 

[jay moussy]

What about dimming LED's ?

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?