moment, the user sees the flash at the same spot in the rotation of the shaft
and the persistence of the eye remembers this until the next flash making
the shaft appeared to be stopped. As the target is rotating there is some
movement evident during the strobe flash. The longer the flash duration,
the more obvious the rotation is and this increases the blur.
6.1
Calculang Blur
Blur can be calculated–
if the sha3 is
turning at 6000 RPM, it takes 10 msec to
complete one revoluon. If the strobe
flash duraon is 100 µsec (1/100 of a
millisecond), the sha3 will turn: (flash
duraon/me per rotaon) x 360°, which
is (.0001/.01) x 360 = 3.6°. So you will see
the sha3 appear to move 3.6°.
As the flash pulse widens you will see
greater degrees of rotaon which results
in more blur and a brighter perceived
illuminaon (the LEDs are on longer so the
average light the eyes see is greater). The
trade off is blur versus brightness. The
further away the rotang point is from the center axis the faster
the tangenal velocity and the worse the blur appears to be.
When se8ng the pulse duraon in degrees, what you set is what
you get. Refer to the image on the right for the difference between
a 1° and 5° (of rotaon) flash duraon.
There are two methods of adjusng the flash pulse width and hence
the brightness and consequently the blur. For se8ng Brightness see
Brightness (BRITE) Menu.
24
1°degree of
movement
5°degrees of
movement
