Handbook of High Speed Photography - IET Labs, Inc.

From the measured distance between successive positions of a fixed
point on the shaft in a multiple exposure taken with such a light
source, he could calculate the instantaneous velocity and acceleration
of the shaft. Details of a sample problem and corresponding calcula
tions are shown in Figure 1-4. For a description of the method used
to take a multiple-flash picture, refer to paragraph 5-3-3-
An instrument capable of producing the flashes described is a
stroboscope or a strobotachometer. Such equipment has been available
commercially for many years, and is standard equipment for visual mo
tion analysis in many industries that use machinery with rapidly moving
parts. The stroboscope also has many applications in science and ed
ucation, sports and advertising. Multiple-exposure pictures of the ba
sic motions of various athletic feats, such as the swing of a golf club
or the release of an arrow from a bow, have proven to be most instruc
tive. Some noteworthy examples of this technique may be seen in the
book Flash! Seeing the Unseen by Ultra High-Speed Photography by
Edgerton and KilHan (refer to Bibliography). Multiple-flash exposures
have also proven their worth to advertisers who have used them to lend
eye-catching appeal to illustrations that would otherwise have been
run-of-the-mill. An example of this technique is shown in Figure 1-5.
(Photograph courtesy o{ Daymarc Corporation, Waltham, Massachusetts)
Figure 1-5. Multiflash photograph of a semiconductor diode being at
tracted to a magnetic Daymarc Diode Clip.