Omega Diffusion Question

[Csholl]

Hi,
I was wondering what the difference would be in using an LED light with a diffusion glass in an Omega Enlarger instead of say using a cold light. The cold light doesn't do well with VC papers, but the LED light, providing its the right voltage and watts, I think would be better for this. Would this be practical for using it as a Diffusion enlarger? or would the cold light give more different results?

[Ulophot]

Based on what I've read of the experience of others who have made LED heads, I think your challenges will primarily be two: adequate light intensity and evenness (central hot spot / light falloff toward edges). When you say "an LED light," I'm assuming you mean an LED version of the old-fashioned light bulb. The 212 tungsten photoflood bulb was 150W with abou t7000 lumens. What I see listed now is 150W LEDs with fewer than half the lumens. The 212 was 3400K; LEDs of the bulb type may still have a green spike that will lower the contrast with VC papers. You'll have to try it out.

Hope this helps.

[Robert Bowring]

Instead of trying to rig something up it would be easier to just get a color head for your enlarger. It is a diffusion head and can be used for printing with variable contrast papers.

[Mal Paso]

The nice thing about LED is the lack of Infrared which is 90-95% of a tungsten bulb's output. You don't need IR absorbing glass and glass negative carriers to control negative pop because there isn't any.

Cold Light is an arc through mercury vapor illuminating phosphors coating the inside of the bulb to produce visible light and the output is unstable. The better heads use a photo cell to monitor output and adjust exposure time. Output is low so tubes are close to the diffusion glass and sometimes can be seen in the print.

I converted a broken cold light head to LED. Voltage is stabilized by a 24 volt power supply so even running an electric heater on that circuit won't change the enlarger's light output. I used Blue and Green LEDs for contrast control, Red for dodging/burning and White for focusing as Blue/Green was too dim. Heiland makes a commercial product but there are a lot of DIY projects on the net including mine.

[jnantz]

I worked for this. little old lady trained in the 1930s, and when I first started working for her she lifted the drape that was blocking all the stuff she had pack-ratted over the years and she pointed to a crate with about 30 long neck light bulbs that her "Burke and James Solar Enlarger" took. in the 60s and 70s she scoured the phone book and bought what she said was a lifetime supply of these bulbs from everyone she found in the yellow pages within a 60 mile radius, and they outlasted her! ..
OP. I hope you find the light source you need, my mentor knew this day would eventually be here! ( she's been dead since the early 90s and enlarging since about 1931, she probably doesn't need those bulbs now ) ... on a different thought, you might find a glass blower/ commercial artist who does neon signs he or she will be able to put xenon ( in day light strobe/flash ) and / or whatever else you want them to put in. cold cathode is just a larger diameter tube but it's the same thing as what people refer to as "neon". (fluorescent tubes before 1938 didn't exist, it was cold cathode back then ).. and maybe "spec sheets" for cold light heads will tell them what gasses to put in.

[Bill Burk]

Zone VI stabilized cold light source is my favorite of all the light sources I have tried for the Omega D2/DII enlargers.

Zone VI did both approaches, a compensating timer that varies the time depending on allowing the light source to fluctuate. And stabilizing, where they vary the voltage applied to the light bulb in a feedback loop so that you can rely on real time.

Both approaches would work. The teal color has Blue/Green component colors which is all you need for multigrade paper.

[Daniel Unkefer]

I print everything on graded RC paper (for now). When printing Forte and Ektalure I used to prefer the Omegalite 4x5 hooked to Olde Lektra Labs and Zone VI (Lektra Labs) Timers with foot switches. Also have a modern 4x5 LED Head, if I start printing big I will switch to that. It also works best with graded paper, so I match the negs to the paper. Looks good to me :)