I know a lot of you use ND filters, I don't know what you are trying to achieve by using ND filters. I'm a pro still photographer and I'm new to video, but the physics of photography is the same in stills as in video. In still photos I would use a ND filter to control some part of the exposure that was not achievable by using the 3 variables to obtain the needed exposure for the effect I needed on a certain photo. On the p3 camera when you put a ND filter on it, which one of the 3 variables does it change? If it changes the iso then your video will have more grain, more noise. If it changes the FPS then it would slow it down which could cause problems with the video. If it changes the aperture then the other two would have to compensate for the change which could put more noise or more flicker in the video. So my question is why do you use the ND filters, what are you trying to achieve by using them?