Possible light source for 8X10 enlarger

[Neal Chaves]

This new product looks like it could be a good light source for existing or home-brew 8X10 enlargers. It has three "contrast grades" built in. I have a 5000K tube in my Beseler cold light head and I have it "zeroed out" to grade 2 VC with a 30Y Rosco gel. I add more yellow to reduce contrast. To increase contrast I replace with 10Y, then no filter, and then start adding magenta. If this new panel has enough output for enlarging it could be very useful.

http://www.omegabrandess.com/products/Braun/10320

[Tin Can]

The price is right.

Let us know how it works.

[Eric Woodbury]

With only a 10W power source, this source is bright enough for direct viewing, but I'd guess 3 or 4 stops short of sufficient output for projection. This is only my educated guess. YMMV.

ew

[Peter De Smidt]

I'm afraid I agree with Eric. You might consider using a light meant as a photography light instead of a slide viewer, something like: https://www.bhphotovideo.com/c/product/1172653-REG/aputure_ls1sv_light_storm_ls_1s.html

[Tin Can]

Just to obfuscate, here is my 2014 big head experiments. I used only 20 watts. The Fotar was sold to a guy who HAD to have it this year just before I almost moved the monster. It is the best 10x10 chassis I have seen and owned. I have 3 other designs in hand. But I did not like the Fotar counterbalance cabling design and excessive ballast. It was perfectly in alignment without adjustment, as checked by the laser gizmo.

Not sure if this thread has the lightbox experiments. http://www.largeformatphotography.info/forum/showthread.php?110376-Hacking-8x10-and-11x14-enlarger-LED-head&p=1100925&viewfull=1#post1100925

[jose angel]

With only a 10W power source, this source is bright enough for direct viewing, but I'd guess 3 or 4 stops short of sufficient output for projection. This is only my educated guess. YMMV.

ew
Agree. I think my LED light source is near 20 watts for 5x7", and it`s ok but not so powerful, at least for big prints. If this one is 10 watts, for 8x10" it`s also my guess that you could need quite a few minutes of exposure to print a negative.
Also, I don`t see the point of having color temperature control, and the price seem to me way off for such product. Mine was made for less than EUR 30, and similar sized ceiling lamps for room illumination use to cost no more than EUR 40-60 around here.
Excuse me if I`m a party pooper, just my sincere opinion.

[xkaes]

An earlier post on a different thread mentioned that his Beseler 8x10 used 12x12" filters. I don't know if that is true, but that might be a consideration -- and 12x12" VC filters can still be obtained. I cut some down to 7x9" for my CB7.

[Eric Woodbury]

True about color temperature. With white LEDs, one is shifting a lot of energy to a useless part of the spectrum (red) and then using inefficient filters to get the contrast control. Better to start with 'royal blue' and green LEDs.

A good resource for building your own is LEDsupply.com. Good prices and reasonable shipping policy. Look at the kits for grow lights. I wouldn't use one straight-away, but see what they've done and adapt to your needs. They have triplet star LEDs in royal blue and green, bolt-on heat sinks, power supplies, etc. I'm working (slowly) on one now of my own design using their LEDs and heatsink. 9 + 9 blue/green LEDs. Good for over 100W. Mounted up for use with 5x7. I'm suspicious it is too bright by at least 2 stops, but I have not printed with it yet. I've designed the controller, but still need solder the parts together. Simple to build. All analog, so the number of connections is minimal. I'll keep you posted and I'm willing to share design. I even have the LTSPICE (analog circuit simulation tool, free) file for the adventurous.

Keep up the good work.
--ew--

[Peter De Smidt]

Eric's approach has a lot of merit. I look forward to seeing the finished project!

[Eric Woodbury]

...and if it doesn't work out, grow your favorite plants inside. Dual use.

[xkaes]

...and if it doesn't work out, grow your favorite plants inside. Dual use.

And if you happen to live in Colorado, or several other similar States, you could make a profit -- and afford a factory made enlarger!

[Tin Can]

Eric, sounds great.

Thanks!

[Harlan Chapman]

These LED strips perform brilliantly as a light source for a large format enlarger. Testing contrast filters from 00 through 5 printing a projection step wedge the gradation is nice through the entire range. They are extremely bright too:
https://www.superbrightleds.com/moreinfo/variable-white/tunable-white-led-strip-light-reel-color-temperature-changing-24v-led-tape-light-511-lumensft/3831/7935/#tab/Specifications
They are tuneable but don't bother with that. Best to combine the cool and light terminals at full power. Adding the color temperature controller cuts output and doesn't improve performance.
I just finished building and testing a head for my 4x5 enlarger with these and am very pleased with the results.
I built a head for my 8x10 enlarger using an earlier iteration of these LEDs, slightly less bright and not quite perfect with contrast control but very much good enough. I applied them to a 1/2" thick aluminum plate to act as a support/heat sink. Built a 3" high box from hobby plywood to hold it above the diffuser. Used connectors available from the vendor to wire each strip as you can see in the photo. A huge improvement from the original 600W tungsten halogen beast of a head that needed a cooling fan and stood a foot higher. The LED head is faster as well.
You need to size your power supply properly and wire it to a relay so the LED power supply can stay on and the relay can switch the LED power supply output on/off with the output of your enlarging timer. The power supply itself shouldn't be powered by the timer as it will flicker and give poor control.
Print well,
-Harlan
172727

[Peter De Smidt]

https://www.dropbox.com/s/p720ade21a93av0/DSC_2206.jpg?raw=1

Yes, this is probably the easiest way to get RGB control. Red is useful for positioning fancy dodging tools under the enlarger.....