User Manual

10. Application information
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10.2 Apparent direction of movement
The direction (clockwise vs. counterclockwise or forward
vs. backward) at which the object appears to move is
determined by the flash rate, the object’s actual direction of
movement and the orientation of the stroboscopic beam to
the object.
Example:
Assume you wish to visibly slow down the movement of a
fan which is rotating clockwise at 1,000 RPM.
Case 1: If you stand in front of it and strobe it at a rate of
1,005 flashes per minute (FPM), the object will appear to
be moving at a rate of 5 RPM in a counterclockwise direc-
tion.
Case 2: If you stand in front of it and strobe it at a rate of
995 FPM, it will appear to move at a rate of 5 RPM in a
clockwise direction.
Case 3: If you stand behind it and strobe it at a rate of
1,005 FPM, it will appear to move in a clockwise direction
at a rate of 5 RPM.
Case 4: If you stand behind it and strobe it at a rate of
995 FPM, it will appear to move in a counterclockwise
direction at a rate of 5 RPM.
10.3. Harmonics
If you continuously increase the flash rate while strobing an
object, it may appear to freeze, slow down, speed up, go
forward, freeze again, go backwards, form multiple images,
etc. These images appear at mathematically determined
multiples or harmonics of the object’s actual speed.
Example:
Assume you wish to slow the motion of the fan used in the
last example, but you want it to be brighter.
Technique: Starting from 1,000 FPM, slowly increase the
flash rate. At 1,500 FPM the image will appear to freeze
again. Continue to increase the rate.