LED bulb in enlarger ??

[Yourix]

Hi there
This topic has been discussed a lot in the past but technology goes fast and I was wondering if in 2024 there was a realistic low-consumption/low-heat LED bulb alternative to our traditional incandescent bulbs...
Of course for multigrade paper we need something with very particular wavelength or filtering won't work as expected...

I've read somewhere that "Osram Parathom 4000K LED 10w " was delivering consistent results with no variation in grading when compared with tungsten bulb.
Does any of you work with a LED bulb in his enlarger ? With which results ? And if yes, which bulb ?

Multigrade/color head, cold head and Heiland products are not what I want to talk about... Only traditional enlargers with condensers and a bulb as a light source.

Thank you

[maltfalc]

rgb bulb, instant colour head.

[Yourix]

Yes, but what if I don't want a bluetooth-smartphone-app-controled-prone-to-failure-thingy ?
The beauty of wet printing is his simplicity. Basic technologies that can hardly fail.
RGB LED light source is tempting but i want KNOBS to control it or i'll stick to my filters.

[Drew Wiley]

You'd probably have to test that postulate for yourself. Those bulbs aren't very expensive anyway. But how do you intend to accommodate VC papers?
With a filter drawer?

[Joshua Dunn]

Yourix,

Beseler has created a light source to do just what you describe. Their LED Dichro 45SL head operates as a traditional color head.

-Joshua

[Tin Can]

I bought a 23C new in box with cigarette smoke

In the middle of the Great Discard when many tossed Enlargers

The 23C eliminated all vibration

I will not disclose the very low price hand delivered from eBay

Yourix,

Beseler has created a light source to do just what you describe. Their LED Dichro 45SL head operates as a traditional color head.

-Joshua

[Drew Wiley]

Joshua, he said he didn't want a color head. He's apparently just looking for an LED replacement lamp to the old opal bulb. Any of those beehive style heads are going to be dependent upon either a filter drawer or filters under the lens for selective VC control.

[Joshua Dunn]

Drew,

My mistake.

-Joshua

[Louie Powell]

LED lamps have different spectral output compared with incandescent lamps, so the response of VC papers and filters would be different. But that would be true if you just replaced an old incandescent bulb with a similar new one - the color temperature would change slightly causing the response of VC papers and filters to be slightly different. I wouldn't worry about that - I was taught to ignore the number on the filter, and instead run some test strips to determine the response of the paper and the filtration required for individual prints.

But what I would worry about is that the design of LED lamps typically has to address the issue of flicker. Specifically, LEDs are DC devices, so lamps include rectification to convert AC power to DC, and that leads to the need for smoothing capacitors to maintain an approximately constant voltage on the LEDs themselves. The issue is that when you switch off power, that capacitor discharges slowly, causing the light output from the LEDs to taper off rather than switch off instantaneously. Better LED lamps include provisions to force that capacitor to discharge more quickly, but there is still a tendency for LED lamps to fade to dark.

In a conventional enlarger, the output of the lamp is controlled by an external switch - usually a timer. So the problem is that if an LED is used instead of an incandescent source, the output of the lamp will fade down rather than be switched off. If the printing time is minutes, that fade down won't be an issue, but if the printing time is seconds, it will. I assume that a few manufacturers have recognized that there is still a market for lamps that go off when you turn them off, and make lamps that work that way. But most of the lamps you see at big box stores and supermarkets will have a pronounced fade-down characteristic that makes them unsuitable for use in conventional enlargers.

[Mark J]

If you're using MG paper, you need to make sure the LED bulb has a decent amount of energy at or below 450nm ( ie. deep blue & violet ). Otherwise you won't be able to get the harder grades when you need them.
Some LEDs do not do this ( check the spectrum of what you are intending to use ).
This whole subject has been discussed several times before, in the context of DIY LED-based conversions, so do a search for more information.