Actually something is coming back to me. Its useful for "day for night" shots. Originally one would slap a blue filter on your lights and under expose the foot

Actually something is coming back to me. Its useful for "day for night" shots. Originally one would slap a blue filter on your lights and under expose the footage by x amount. Assuming the sensor has a dynamic range wide enough, you can just alter the exposure in post, without clipping the blacks too much.