Powerfull and easy to use ring light for a Canon 16-35mm lens.
This is for LED-Rings from China (search for "LED Ring White Angel Eyes").
Power for mobile use: 3 rings will need about 500mA at 12V and full power. The battery/LiPo needed will be to big/heavy to fix it directly on the ring light (my opinion). I will design a belt module (for your belt or the camera strap) with a LiPo (4S or with boost-converter) and a Microcontroller for PWM dimming.