Anyone here ever used a "ring light" -- the kind that go around the lens? I've used the for still photography but never seen them used for cinematography (although I'm new to cine). Is there such a thing?
Yup... I have one and I use it relatively frequently.
Ours however is completely homemade... basically out of an aluminum cake pan and all the electronic bits that it needs to work. We made one ourselves because the "real" ones were 1) quite hard to find and 2) incredibly expensive.
We have color-corrected tubes for both daylight and tungsten... and did the necessary electronic voodoo to make it both flicker-free and dimmable (at least down to about 50%).
It's not real pretty, but looks like this....
It's pretty useful indoors at about 12 feet or less, just as a bit of a beauty light or eyelight. It gives a really nice look, except I quickly learned not to try to use it with talent wearing eyeglasses... the circular reflections it creates are pretty creepy. With EXTREME closeups you can also see the reflections in bare eyeballs, but it's usually not an issue.