Great test!

It only confirmed my opinion that MicroHalogen is the best choice among the budget lights. I would much rather have two MicroHalogen than 10w Halogen alone. I'm hoping somebody will make a helmet mount version of MicroHalogen with a separate battery holder.

I believe the camera 2manybikes uses works for this purpose because the camera taking all the photos with maximum brightness setting(maximum aperture, slowest shutter speed) that the camera can give. If the scene gets any brighter, the camera will start adjusting the exposure automatically.