As a home based amature interested in
film, I'd like to know
about slow motion. When I watch a film, I always love the pure, smooth slow
motion that is used sometimes (not the blur, stop, blur, stop slow motion).
Yet at home, using DV video and editing software (Final Cut Pro), when I try
to make slow motion the product is the blur stop blur - elongated frame way.
I wish I knew what I'm missing and an understanding of the way film slow
motion is done. Take note that my camera does not have a shutter
Film slow-mo is done by increasing the frame rate from 24fps (standard)
48, 96, 1000 fps.. whatever. 48fps would give you x2, 72 fps x 3 etc. This
is "pure smooth" slow-mo because the image is gathered at twice (sic) the
speed it is projected: each frame is "captured" 2x, 3x etc in the original.
The "blur stop blur" thing happens when you stretch the original normal
speed footage (or video) and print or render it twice or 2 1/2 times,
creating an artificial slow mo. The shutter speed adjustment available on
some video cameras, affects the motion-blur of each individual frame
("sports mode" etc), but this has nothing to do with slow motion. Video
slow motion is a technology that is improving rapidly (watch any tennis game
to see it in action), but is currently very expensive to implement, and
still not as good as film.
Is it possible to shoot video at high speed to form slow speed?
No! (well not on a low end video camera). The only way to slow
video is to play it back slow and re-record it.
This is course, does not give the same quality as film..
There is work going on to improve this situation but someone else would have to tell you what this is.
(Actually there are slo-mo hard disk systems around now)
What do you think of effects like slo-mo and time lapse? Useful?
Overdone? Are all of those effects created in the filming process, or can
some of them be done in post-production? --Matt
When Sam Peckinpah introduced slow-mo in The Wild Bunch to the wider
audience it was sensational. When Antonioni ended Zabriski Point with the
entire contents of a house flying though the sky at 300fps it was the most
memorable visual in the movie. Now it’s just another available tool which
is sometimes used well and sometimes badly. I like it when it’s appropriate
- I use subtly different frame speeds quite a bit, so technically it’s a
slo-mo shot but the audience wouldn’t see it that way. Most explosions can
be shot up to 50fps without noticing that it is particulary slow. Different
frame speeds are used all the time in fights and action work. I did a
sequence of a man falling down many flights of stairs where we followed the
falling man with a steadicam, and racked the frame speed from 6fps to 30fps
(with aperture compensation so the exposure wouldn’t change) quite
violently. This greatly increased the sense of buffeting in the mans
descent of the stairs - something the stunt man couldn’t have done without
hurting himself! But it didn’t show as an “effect”.
Time Lapse is very different, as this is always obvious to the viewer
what it is, so it tends to be used more in documentary and wild life
photography, as well as scientific research.
Both these effects are not possible with any decent quality in the digi
world: you can change film speed quite a bit in post-production but it
becomes apparant if you move more than 50% away from the original speed in
the slow direction, but you get away with more if you are speeding things
up. Progress is being made with slo-mo in the Digi world, but it’s still a
long way from what you can do on film.