Cha
p
te
r 7
SR Mot
ion
(Wi
th
HKS
R
-10
2
In
s
talle
d)
80
7-1 Overview
Relation between the target frame
frequency and the number of frames shot
To obtain the desired slow and quick motion effects, it is
necessary to set the appropriate number of frames
according to the target frame frequency. To obtain quick
motion effects, shoot with undercranking. To obtain slow
motion effects, shoot with overcranking.
Example at the target frame frequency of
23.98PsF
To obtain quick motion effects:
Set the number of frames
to 1 to 23 FPS.
To obtain slow motion effects:
Set the number of frames
to 25 to 60 FPS.
For example, shooting at 60 FPS causes playback in slow
motion at 0.4 times normal playback speed.
Relation between the target frame frequency and timecode
When the system frequency is 23.98 Hz, timecode
normally advances from 0 to 23 frames. This becomes the
timecode of the recorded material (target frame
frequency). If the rate at which timecode advances is not
constant within the recorded material, a timecode
discontinuity occurs at playback time. For this reason, set
the target frame rate at recording time to the same value as
the timecode at playback time.
In SR Motion shooting, it is possible to set the target frame
frequency and the system frequency at recording time to
different values.
For example, if 60 frames are recorded with the target
frame frequency set to 23.98 Hz and the system frequency
set to 59.94 Hz, then 60 frames per second are recorded,
but the timecode does not advance from 0 to 59 frames.
Instead, it advances from 0 to 23 frames, which matches
the target frame frequency. If one second is recorded with
these settings, beginning with second 00 frame 00, then the
timecode advances quickly from second 00 frames 00 to
23, and then continues to advance as second 01 frames 00
to 23, and finally as second 02 frames 00 to 11, at which
point 60 frames have been recorded (see the following
figure).
When a tape recorded in this way is played on a VTR that
has been set to a system frequency of 23.98 Hz (the tape is
played at a target frame frequency of 23.98PsF), then the
video is 24/60 = 0.4 times normal speed. But the timecode
advance by 1 second in the space of 1 second. Even if the
slow-motion section follows a section recorded at normal
speed, the playback timecode is continuous and no
discontinuity occurs.
Operation of SRW-1 during slow and quick
motion shooting
During slow and quick motion shooting, input data is
stored in the memory of the HKSR-102. Transfer of the
data to tape starts when a specified amount of data has
been stored. Therefore, the tape does not run for a short
time after recording starts. The tape starts running when
data transfer from the memory starts, and stops running
60
FPS
30
24
FPS
1
Target frame
frequency
Frames/second
Slow motion
Normal speed
playback
Quick motion
24 frames in total
24 frames playback / 60 frames recorded = 0.4 times normal speed
S59P(23PsF)
Record at 60 fps
Play back at 23 PsF
60 frames in total
1 second played back
1 second recorded
Содержание HKSR-101
Страница 126: ...Index 126 Index ...
