Stroboscopic
photography is a rather more abstract branch of photography,
consisting of a flashing strobe light and a camera with
an open shutter. Stroboscopic photos must be taken in
darkness so that everytime the strobe flashes, a still
image is taken of a moving object at that instant.
On
the right, a friend is captured on camera while moving
her arms down with Penguinslab's newly modified strobe
light. The strobe light was simply one bought from an
electronics store, but I had to personally modify it
internally to increase the maximum flash rate to ~20Hz
(originally 10Hz). |
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Here, a
ball's trajectory is clearly seen after being fired
from a stationary position. The gaps between each image
of the ball is about the same, suggesting a constant
speed.
An exposure
of a few seconds constitutes many flashes of the strobe,
and hence movement of the object can be recorded through
a series of images. The flash rate of the strobe determines
the time between captures of an image, and can be adjusted
according to the speed of the object to be captured.
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The
strobe light is not bright enough when the flash rate
is high, as is in the photo to the right. I had to increase
brightness on this photo using software.
It
doesn't take a pro soccer player to see that the ball
is quite flat, in fact very flat. The fact that the
images of the ball are more bunched up at the top of
each parabolic bounce is evidence of a decrease in speed,
which should be fairly obvious... |
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Very
self explanatory photo here... a hammer striking a nail.
Although it does look like I almost missed it... remember
this was in complete darkness with the only source of
light being the strobe light itself, whose flashes can
be very intense. I usually wear dark glasses while taking
these photos. |
Depending
on who you are, and how you interpret images, this photo
to the right could look like a syringe or a balloon
taking off or all sorts of things (according to comments
I have received about this). It is, in fact, none of
those things. This is the same hammer as the picture
above, but this time levering the nail out of the wood
using the other side.
The
nail is visible clinging to the end of the levering
arm in each capture. |
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Stroboscopic
photography can also be used for high speed purposes,
like taking pictures of the bullet from the coilgun,
for instance. This bullet was actually ejected at a
very low speed, because if the power to the coilgun
was turned any higher, the strobe light could not flash
fast enough to capture anything. A higher speed stroboscopic
photo of the bullet can be found on the coilgun
page. |
Similarly,
here is a photo of the trebuchet
in action. The angle at which the counterweight swings
up to can be observed, and the maximum deviation of
the throwing arm can be seen likewise.
Unfortunately,
the strobe light was not bright enough to be able to
illuminate the pouch and projectile at all, so that
portion was cut off. |
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Back
to the hammer! It is not that hard to see that this
is simply a hammer hitting a golf ball off a plank of
wood. |
Hmmm...
my fingers are taking a stroll. I admit this photo can
be confusing if you have no idea of the context! |
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What is
going on here?
Answer:
A plastic
ruler is originally placed leaning against a wall (the
brightest white stripe). I go to grab it (see the hands
going towards it from the right?) and the ruler can
be seen moving, and immediately after that I grasp the
ruler tightly and take it away. |
