Fifteen surface mounted LEDs (5 groups coupled in parallell with 3 diods + 1 resistor coupled in series in each group)
They came in many different sizes and I ordered the smallest one they had (60mm diameter). I paid less than €10 for a couple, shipping included.
They are intended for 12V but work fine with a regular 9V battery if you want a very small package. You get a little more output if you short out the resistors like I've done to the one on the right (I guess you could easily replace them with potentiometers if you want to control the different groups separetly):
For convenience I hooked mine up to a 9V battery case with built in on/off switch (cost: €1).
I guess it's pretty obvious how you put these to use but here are some examples anyway:
(yes, that is a Danone bottle
)
Inner diameter happens to fit nicely onto my 39mm extension tubes – a rubberband bushing keeps it "steadyish".
The LED:s emit a very wide light cone so you might want to add a reflector to reduce light loss – on the other hand this can get in the way more if you want to add flashes etc.
Obviously nothing revolutionary here but it's cheap, simple, lightweight and low profile. The downsides are that they aren't very bright and though it's of course perfectly possible to use this as the main exposure lighting you'll end up with fairly long exposures. I use them as focus aid lights though oftentimes a single, bright, narrow beamed LED is more convenient for my kind of photography (in the field when you need to be able to get really close to the ground etc)
/John
PS. if you're interested in giving the ringlights a try– just do an eBay search for "Angel eyes" in the vehicle category.
