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Sometimes blurred images suggest action
more effectively than pin-sharp ones. But if a moment is to be caught
from a movement and held, sharp and clear, some thought must be given
to the shutter speed required to achieve this. You may be trying to
freeze the animated gyrations of children at play in poor light which
restricts you to relatively slow speeds. The following facts may serve
as a guide.
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Suppose the child is running across from
side to side at something like four to five miles an hour and about a
dozen feet from the camera. A speed of 1/200 sec. is needed to arrest
movement. If the child is on a roundabout, or trotting on a pony, or
cycling, you may well need to set your shutter at 1/1000.
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If the lighting conditions are bad this
might be out of the question. But these times presuppose that the
background is also to be sharp. But if the camera is swung, or panned,
with the moving child, speeds as slow as 1/30 can be used, after
practice. The resulting blur of the background suggests speed more
effectively than the picture in which everything is sharp.
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Slower shutter speeds may also be used if
the child is moving towards the camera or even diagonally across the
picture area, rather than parallel to the focal plane. In some cases
fast movement can be stopped by careful timing of the moment of
exposure. A jumping child, for instance, if caught at the peak of the
jump, is momentarily still, before starting the downward movement, and
relatively slow speeds may be used to catch this moment. This also
applies to a swing or see-saw at the peak of the movement. I was once
able to freeze an equestrian act, full of violent movement, in the
relatively poor light in a circus tent, with a Bhutto speed of 1/3o
sec. Three horses galloped round the ring, a pyramid of men and girls
on their backs. The picture was taken as they reached the left-hand
side of the ring and, for a brief moment were galloping towards the
camera.
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Movement can, of course, be stopped by
flash, but here we have been mainly concerned with taking pictures
without the knowledge of the children.
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