So at work we recently purchased a Nikon D3s (very happy.) However I'm struggling to understand how changing the shutter speed 'works' when shooting video. Unlike with a photo or camcorder when shooting on the DS3 lowering the shutterspeed to 1/3 doesn't appear to create any motion blur.
What I'm wondering primarily is, what is the optimal shutter speed when shooting video, does it vary depending on how many fps the video is recording at?
[Rob Wilson]"What I'm wondering primarily is, what is the optimal shutter speed when shooting video, does it vary depending on how many fps the video is recording at? "
Bingo! To better emulate the the shutter of motion picture film camera you'll get the most filmic look and most natural to your eye if you observe the 180 degree shutter rule.
So lets say you shooting 24fps your shutter speed should be 1/48. Or lets say your shooting 60fps your shutter should be 1/120. Now many DSLRS are not going to give you that exact number instead of 1/48 you'll probably have to go for 1/50. If you start using faster shutter speeds i.e. 360 so 1/100 for 24fps you'll notice the footage might flicker a bit and have a harsh "Video" look to it.
The thing a lot of photo folks making the move to video don't get though is shooting 180 degree and at apertures needed to have nice out of focus backgrounds (or even moderately blurred ones) you'll often have to much light entering the camera. This where lighting as well as using matte boxes with the ability to drop in different staged ND filters becomes really important. Also just like like in photography controlling the ISO will allow you to control exposure.