Dimmer for Modern Enlarger Lamps LED Head (Model 2).

Tried this over on the other forum and got some helpful responses but not a "plug 'n play" solution. Tried Cree but no luck there. I was hoping there would be a 24V, 40W power supply with built-in dimming capability so I could tame my Model 2. I had always used a 75W bulb and the Model 2 approximates 150W which makes it difficult to stay in the f8-11 range at about 10-12 seconds which I prefer. I am leaning more toward diffuser or nd filter since i can't decipher the spec sheets from the dimmers out there. I thought it would be a simple pulse width modulation but ??? Any experience?

Joel

Remember the color of your light will change when you dim it. As photographic materials are most sensitive to Actinic or blue light waves changing the amount in the light mix of your light source can also change contrast etc. Adding a sheet of ND material from Lee or Rosco may be a better solution than a dimmer.

Rod Klukas said:

Remember the color of your light will change when you dim it. As photographic materials are most sensitive to Actinic or blue light waves changing the amount in the light mix of your light source can also change contrast etc. Adding a sheet of ND material from Lee or Rosco may be a better solution than a dimmer.

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Ponysoldier said:

Tried this over on the other forum and got some helpful responses but not a "plug 'n play" solution. Tried Cree but no luck there. I was hoping there would be a 24V, 40W power supply with built-in dimming capability so I could tame my Model 2. I had always used a 75W bulb and the Model 2 approximates 150W which makes it difficult to stay in the f8-11 range at about 10-12 seconds which I prefer. I am leaning more toward diffuser or nd filter since i can't decipher the spec sheets from the dimmers out there. I thought it would be a simple pulse width modulation but ??? Any experience?

Joel

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Ponysoldier said:

Tried this over on the other forum and got some helpful responses but not a "plug 'n play" solution. Tried Cree but no luck there. I was hoping there would be a 24V, 40W power supply with built-in dimming capability so I could tame my Model 2. I had always used a 75W bulb and the Model 2 approximates 150W which makes it difficult to stay in the f8-11 range at about 10-12 seconds which I prefer. I am leaning more toward diffuser or nd filter since i can't decipher the spec sheets from the dimmers out there. I thought it would be a simple pulse width modulation but ??? Any experience?

Joel

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I tried the lowest-power ES27 LED mains voltage lamp I could find - I think it was a Philips 6 Watts, about the size of a golf ball - in my Agfa Varioscop 6x9cm enlarger’s condenser lamphouse (I normally use a 75W or 150W Photocrescenta lamp) and it worked great (I got good, even negative carrier illumination and no heat) but it was still WAY too bright, demanding impossibly short exposures when making smaller prints. The test and final prints that I made with it (Ilford FB MG WT) looked fine nonetheless and contrast control with gel MG filters seemed to work fine at around G3.5. I think it’s still early days with these lamps and I’m yet to see a suitable plug-and-play ‘line’ dimmer which can be used with them. These lamps seem to be intended for general indiscriminate household lighting so I guess that the manufacturers don’t see a need to produce a suitable ‘line’ dimmer for them, but sooner or later one will come, I should think. Andrew

It is not early days for LED lamps. At the home stores in Canada it is almost I possible to get incandescent lightbulbs. The 100 year old incandescent bulb factory in Ontario closed last year.

Dear Joel,

Maybe this will help. Be sure to avoid systems that dim by varying the voltage.

Good luck,

Neal Wydra

Thanks for the responses. The only reason I even considered using a dimmer was that Cree indicated that the color temperature remains remarkably consistent across a very wide range and I interpreted that as an indication that the variation in light output was due to changing the pulse width while keeping the other variables constant. The Cree XP G LEDs were selected by the designer for their 3400 degree K color temperature to also use with VC filters. Cree has subsequently replaced the series with an even higher output LED!

Joel

Thanks Neal. I will talk with the folks at Mean Well. It looks as if the 40 Watt could be the right direction since it seems to hold voltage constant while varying pulse width.
Joel

Ponysoldier said:

Thanks Neal. I will talk with the folks at Mean Well. It looks as if the 40 Watt could be the right direction since it seems to hold voltage constant while varying pulse width.
Joel

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You should keep the current constant and not the voltage. The voltage across an LED is always the same. As you increase the voltage the current goes up until the amount of voltage drops in the series resistor and keep the voltage across the LED the same.

Have you considered a DC light? Theres all manner of flash lights. Maybe a LED bulb for a 12 system like a RV or motor coach.

Ponysoldier said:

Tried this over on the other forum and got some helpful responses but not a "plug 'n play" solution. Tried Cree but no luck there. I was hoping there would be a 24V, 40W power supply with built-in dimming capability so I could tame my Model 2. I had always used a 75W bulb and the Model 2 approximates 150W which makes it difficult to stay in the f8-11 range at about 10-12 seconds which I prefer. I am leaning more toward diffuser or nd filter since i can't decipher the spec sheets from the dimmers out there. I thought it would be a simple pulse width modulation but ??? Any experience?

Joel

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Have you tried the Modern Enlarging manufacturer?
His website seems to be available again.

Tried contacting them but didn't receive a response. I suppose I will resort to the ND filter (gel above the negative stage). Thanks for the follow up!
Joel