compact modified halogen video light

I call it the Riegel.CP (to follow the naming scheme for the light's I've built: Riegel and Riegel.LR):

http://marokero.com/Riegel.CP/

This time around I wanted to attain a very small form factor, utilizing a ready made enclosure, in this case, Bescor's MPL-12V. It's a very small light, and after modifications it's barely 3/8" wider and 1/8" longer than the original. Plus it has separate controls for the dual white and single red Endorstars. That way I can adjust the warmth of the light for use in doing portraits in dim light. The battery I employed is a LiFePO4 type with 84Wh capacity, and theoretically it could feed the light for 3-9 hours. I say theoretically because there's a problem with heat build up. Because I used a ready made enclosure and wanted to maintain the small form factor, I was limited on the heatsink size, and also no fan. I may need to add a fan as the light can reach 80C+ in just five minutes at 100% output! That's not good for the leds, and definitely not good for the other components. Not shown in the photos is a small fiberglass circuit board (thermal insulation) I cut to size and inserted in between the heatsink and the components. Hope that will help in the time being.

I have a few weddings coming up this weekend, and I want to see how this works both for me and my videographer friends. They absolutely loved my previous light, but wished there could be a dimming feature. Once I get the heat issue under control in the next version, I just might sell a few to my friends.

Output wise, this is what I've measured using my Sekonic L-358:

white leds & r/o at 100% -> ISO 200, 1/60s, f/1.4, @ 1.2m (4ft) distance

white leds & r/o at 100% -> ISO 200, 1/60s, f/1, @ 1.8m (6ft) distance

white leds at 50% & r/o at 25% -> ISO 200, 1/60s, f/1.3, @ 1.2m distance

white leds at 50% & r/o at 25% -> ISO 200, 1/60s, ERR*, @ 1.8m distance

The error in the last test is due to my light meter not registering below f/1 I suppose. That should work out fine at ISOs 1600-6400 and f/1.4 with my camera. I hope to get some good shot this weekend to post here later next week.

I've decided that the light was getting too hot for prolonged use, and it needed a few changes. I've updated the gallery to show the modifications I'm making now:

http://marokero.com/Riegel.CP/content/IMG_0366_large.html
http://marokero.com/Riegel.CP/content/IMG_0368_large.html

In photo #29 I cut a hole at the top of the enclosure to improve airflow - I already put an order for a 50mm fan and grill to install atop the light. You can also see in the background the temperature the heatsink reaches in under 5 minutes of use: 74.4°C! The fiberglass board I put to help shield the heat from the heatsink offers little help, being less than 10°C cooler than the heatsink itself. But if the heatsink can soar past 80°C, that thin layer of protection does nothing to protect the components during extended use. Speaking of components, in photo #30 you can see some detail of the led drivers and voltage regulator I used. It's a switching voltage regulator and it doesn't heat up like regular 7805 regulators - I really didn't need any more heat in the build. Everything is crammed together to fit inside the enclosure. Anyway, after I install the fan and grill I will update the gallery again.

Well done! And you have that very small form factor going here for sure, that is a plus. I can tell that you have been busy with the saw and drill The 50mm fan sounds just right to cool it down. Did you get a 50mm finger guard, too? Also, are your whites the cool whites? We all want to see some 'beam shots', of course. Very nice light you have built! Jeff

Thanks Jeff. The fan grill should be enough to prevent fingers from accidentally touching the blades. The Endorstars are neutral white, and the frosted glass in front helps diffuse the light a bit. I could have put another 50mm fan I have, but that one pulls 2W and is too loud - I didn't want the runtime to suffer too much, nor did I want fan noise being captured on video.

Alberto T.