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Taking pictures with the joker² light barrier system
Copyright eltima electronic 2022
Plane of focus is parallel to the flight path
For subjects moving at high speeds, if
possible, the flight path should be parallel
to the plane of focus. Using the example
of bird photography, the advantages of
this setup becomes clear.
Due to the shutter lag of the camera and
the birds speed, in a situation as in Figure
26 the bird will be imaged some distance
away from the light barrier.
As long as the flight path is in the plane of
focus, the bird will be photographed in fo-
cus regardless of its speed.
Taking advantage of the geometry of the subject
The detection rate will be at its highest
when the light beam is oriented so that it
crosses the broadest side of the subject
profile. This becomes clear in the follow-
ing example.
Birds in flight with their wings spread out
are much wider than tall when viewed
from the front.
If the light barrier is positioned vertically,
then with only one beam an area, here
marked blue, can be covered which is al-
most twice as wide as the wingspan of the
bird, and as high as the working distance,
see Figure 27.
With a horizontal beam, the area cov-
ered with a single beam is much more
limited because the bird can easily fly
over or below the beam, see Figure 28.
Figure 26: The plane of focus is
parallel to the flight path
Figure 27: Bird photography with
vertical light beam
Figure 28: Bird photography with horizontal beam