Some may have seen my babbling on LED enlarger heads and diffusion plastic panels.
I have read, stolen and used all the sources here and elsewhere to get where I am now. Thanks to Konakoa, Jerry Bodine, Ginette and several I am forgetting.
Basically I started this adventure with a $295 Fotar 10x10 enlarger chassis, that I could not resist, from Jack's Camera in Indiana. Pickup only, no head. It is in great condition, but very heavy and a beast to wrestle, at that time I could barely walk or help load or unload. Got it set up and figured I would make a DIY head, someday. Seems I finally have done something.
Then I bought LED video lights very similar to this current eBay listing, which looks the same, exactly the same. http://www.ebay.com/itm/CN-900HS-900...item2c7604af6f
For over a year I built my darkroom and did nothing with the Fotar (it has it's own Zip code, Chicago joke), I did use the LED's as shooting lights. But reading about other's LED enlarger heads got me moving last night.
Pretty simple, I stripped the LED panel of barn doors and other parts, gaff taped closed a lot of side ventilation and light leaks and stuck it on top of the Fotar. I used the barn doors and gaff tape to mask the 12 x 14" bare light to fit the 10 x 10" hole in the Fotar. I used 2 pieces of glass to hold an 8x10" X-Ray neg and put a 12x12" piece of generic 3mm white diffusion poly-carbonate right on top of the glass. The LED's are about 1 inch above that. The light also came with clear, orange and purple diffusion filters that slide into a groove right next to the LED's. see the eBay listing. btw, I think Adorama now has cheaper LED panels.
It works, it works darn good, plenty of power, I had to turn it down to about 1/3 power to get 15 second exposures at F16 with Rodagon 240mm. That's projecting a medium density 8x10 X-Ray neg onto 20x24 inches.
I tried all the filters that came with the LED but have not yet used Ilford Multigrade filters. Orange cut a lot of light, supposedly changing the LED from 5600K to 3200K, purple and clear were similar to each other with less light loss. I was looking for even light coverage. I printed 5x7" pieces all over the 20x24 inch area and so far I like it.
I am not an expert printer by any judgement, so no samples. I did not notice uneven illumination or any evidence of LED pinpoints of light. No hot spots, like I just fixed on my 5X7 Elwood.
I do think this is going to work fine with tuning and I will be using my other similar LED light to make an 11x14 head on another chassis. Don't ask...
I checked power consumption with a Belkin Watt meter and the LED uses 100 watts full blast, but I was printing with 20 watts, creating almost no heat. I may seal all vents and light leaks, or add a box above it with a light trap that allows ventilation, but if I use this rig only for enlarging it will have very little 'on' time, compared to it's normal usage as a video light.
The eBay LED panel is not cheap, but is available and I like the simplicity and low heat levels. This whole thing is easy, a person could make an enlarger chassis from almost anything, look at AA's multi-bulb horizontal enlarger and try this as a modern light source.
The pics show the projection at f5.6, 100 watts, full power. It's bright. The purple filter is in.
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