Just when you think you've seen it all...

"Jay Honeck" wrote in message
news:PZhBf.721145$x96.655433@attbi_s72...
You might want to re-label that video. g

Yeah, that's what happens when you take low-res video with a Canon digital
camera. The shutter speed is actually too SLOW, not too fast, and it
messes with the prop rotation.

Nah. A slow shutter speed would result in enough blur to make the motion
obvious.

The real issue is frame rate, when it comes to the apparent motion of the
prop. I didn't look at the videos in question, but NTSC is 30 frames per
sec (okay, technically it is 29.97). If the prop rotation is the right
multiple of that (in blades per second), the prop will look stopped,
regardless of shutter speed.

The camera is actually taking 60 shots per second, since each frame has an
odd field and an even field. So as far as shutter speed goes, the slowest
the shutter speed can be is 1/60th of a second for the above-mentioned NTSC.
That would be slow enough to get some blur in there. But that would
probably overexpose most outdoor shots, even at an f-stop of 22, unless you
also have a filter to cut the light some. In good light, the shutter speed
could be 1/250th of a second or even faster, which would freeze the prop
without much blur at all.

So, to sum up: any frame rate can be a problem, depending on the actual
rotation speed of the prop. Slower shutter speeds can help, by blurring the
image of the prop a bit, but it won't change whether the individual prop
blades appear stationary or not. However, the photographer usually would
need to take special steps to ensure a slow enough shutter speed; the
default autoexposure on a typical consumer video camera probably won't be
slow enough.

Pete