Converting Omega E3 Cold Light Head to LEDs for $100

[R Mann]

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.

[R Mann]

Closer view of the LEDs mounted on the plate -

[jayabbas]

Nice job on the head. Just curious as to the benefits of an LED light source ?

[jeroldharter]

Excellent work. You should buy up old Beseler or Aristo heads and convert them for sale.

I'm just asking: why not two more rows of 4 LED's on the sides to increase intensity and reduce lateral falloff?

What kind of exposure times do you get?
How do you manage variable contrast filters?
Do the filters behave nicely with the LED's?

[jeroldharter]

Nice job on the head. Just curious as to the benefits of an LED light source ?

LED's don't burn out for a long time, are quiet,, low power, generate little heat, usually don't require a fan. Plus they are compatible with a DIY project. 8x10 light sources of recent vintage are becoming rare. Plus a set of Aristo replacement tubes, just the tubes, for 8x10 VC run ~$1000. So LED's have some appeal.

[R Mann]

Excellent work. You should buy up old Beseler or Aristo heads and convert them for sale.

I'm just asking: why not two more rows of 4 LED's on the sides to increase intensity and reduce lateral falloff?

That is something I considered, but with the fast times I am getting I don't think I need more light. That would also mean adding another power supply. I do think I may try a denser diffusion plate to see what happens.

What kind of exposure times do you get?

Almost too fast - 10 seconds at f22 for an 11x14 from a 5x7 negative

How do you manage variable contrast filters?

I have a set that fit in the E3's drawer - Ilford VCs

Do the filters behave nicely with the LED's?

The results I get are the same as I would get from the other heads I have used. I did a few step wedge test strips for comparison.

[R Mann]

Nice job on the head. Just curious as to the benefits of an LED light source ?

The old head needed new tubes and starters and would have been a little on the dim side. LEDs have very low heat, are instant on with no warm up needed, no "drift" in brightness, and look like a long term solution. I did buy a couple of extras, just in case I did have a few fail - I expect that within a few years Cree would no longer have the exact same unit I am using. One possible problem would be the need to change out all of the LEDs to keep the light uniform. That is one of the reasons I like the solderless connectors, it would be easy to switch all the of the LEDs.

[aduncanson]

Thanks for posting. I have a very decrepit E3 and that cold light head and have been considering just such a conversion.