This post arises from thinking about the various discussions on loading up a smartphone with a filter adapter and neutral density filters and trying to balance the resulting device, which, to make my personal view clear, reminds me of a Rube Goldberg contraption This is liable to be controversial, but here goes anyway... I think that an awful lot of the smartphone video that I see on YouTube would not benefit from a fixed shutter speed and therefore not from the use of neutral density filters. Take the example of 24fps and 1/48th of a second. At that frame rate, the purpose of 1/48th of a second is to emulate traditional motion blur. Motion blur only matters if the subject (a) is moving and (b) is prominent in the frame. If the subject is stationary, or is not moving much, it doesn't matter what the shutter speed is because there's no motion blur to be had. To take a simple example, if the shot is of an urban or rural landscape, I don't think that it matters a wit what the shutter speed is. Also, due to the widespread use of wide angle lenses, a high percentage of the time the subject is not sufficiently prominent in the frame that traditional motion blur will even be visible, certainly not at the size and resolutions at which smartphone videos are typically viewed. I also think that when a specific shutter speed is desired, changing the ISO (within reason), or indeed shooting in more favourable light, is a hell of a lot easier than messing with a filter adapter and filters and trying to balance the result. Just as an exercise, it's interesting to watch a few smartphone videos with this in mind and think about what shots actually benefit from locking the shutter speed at 1/50 of a second (for 24/25 fps) or 1/120 of a second (for the now fashionable 60 fps). All of that said, I'm quite interested in reading other views on this issue.