Converting Omega 5x7 E3 Cold Light Head to LEDs for $100

[rmann]

This is a short description of how I converted an Omega 5x7 E3 Head to an LED head -

The enlarger I have is an Automega 5x7 E3 - it originally had a 4 tube cold light head when I got it. The metal housing is rather compact and has a filter drawer. I removed the old cold light head, but kept all of the original housing. All of the new parts fit into the housing and above the filter drawer.

The LEDs are mounted on an aluminum 3/8 inch plate. The plate was cut to fit into the housing, holes were drilled to use the original mounting hardware from the cold light head.

I made two wood filler blocks that clamp a plastic diffusion sheet just above the filter drawer - I kept the original glass diffusion plate that is below the drawer. I put some metal tape over the wood to reflect light. Yes, There are two diffusion plates - I did this because I wanted to eliminate any hot spots from the LEDs. This has worked out well - light fall off into the corners is about 2/3 of a stop from the center using a R H Designs meter.

I used 12 - LEDs. They are 3 watt units and are wired in series, powered by a Meanwell Power supply. The power supply is mounted above the aluminum plate.

I used plastic LED mounting connectors which allow you to mount LEDs without soldering. You do need to drill holes for screws into the aluminum plate and mount then with heat transfer paste.

Total time to do the conversion was about two days - Cost was approximately $100

12 - 3 watt Cree XP-G cool white LEDs @ $5 Each
12 - Solderless BJB LED Connectors @ $.85 Each
1 - Meanwell LPC 60-1050 Power Supply
Aluminum Plate - I had this in my scrap pile - Maybe $15 if I had to buy it.
Heat Transfer Paste - this I also had, you really need very little to mount 12 LEDs
Wire - this I also had

I sourced the LEDs from: reefledlights.com

They can supply just about all the parts you would need to make a head.

For contrast control I am using a set of Ilford VC filters that I had that fit in the filter drawer. They give me the same control that I had with a conventional enlarger. Print times are fast - about 10 sec for an 11x14 from a 5x7 neg at f22 on Ilford MG fiber paper.

[Ronald Moravec]

I think this is very cleaver.

[jnanian]

nice work !

does your E3 still use the "lens-shutter" ?


john

[rmann]

nice work !

does your E3 still use the "lens-shutter" ?


john

No, when I got it the shutter had been removed.

[Dave Wooten]

thanks

[Jon Shiu]

Great invention and sounds like fun. Do you think the thick aluminum plate and heat transfer paste are necessary for this application?

Jon

[rmann]

Great invention and sounds like fun. Do you think the thick aluminum plate and heat transfer paste are necessary for this application?

Jon

The times the LEDs will be on for focusing could be minutes, my timer has an auto shutoff feature on focus so heat should not be an issue. I did do a few trial time runs and the heat settled down around 115 degrees as measured on the back of the plate. The paste is very cheap and you will need to mount the LED stars on something, so why not use a heat sink of some type?

[Jon Shiu]

I had an idea that it would be easier for me to work with wood using basic tools. Now that I think of it, the heat build up could cause a fire, so not a good idea.

Jon

[ic-racer]

I like the way you fit it all in the original head. Very nice job. I also like the fact you are using the Ilford filters. Just think of the hundreds of hours you would have spend engineering a multigrade dimming and timing circuit, when now you can be printing.

[vpwphoto]

Thanks so much for sharing... my concern/question to you is how even is the illumination... those LED's are almost point sources I figure hot spots may be an issue/// please advise or explain better how you handled this.
Thank you.