On this page I will show you some
of the intentional and unintentional special effects that appear in photography.
Nobody will be surprised seeing the
blurred helicopter blades. After all, they are moving quite fast. Considering
that the tips move at 200 to 300m/s, and estimating the motion during exposure
at 25cm, it's clear that this picture was taken with a shutter speed of
1/1000th of a second. But the interesting part is that two blades look
straight, while the other two are crooked!
The explanation is in the vertically traveling
focal plane slit shutter of the camera. A narrow slit exposes the picture,
traveling vertically over it. The horizontally-oriented blades are exposed
almost in one instant, appearing straight. But the vertically oriented
ones are exposed section by section, moving considerably during exposure!
That's why they look bent.
Looking at the orientation of the leading
edges, it's clear that the blades turn clockwise. So, why is the upper
blade bent forward relative to their turning, and the lower backward? Shouldn't
the top tip have been exposed first? Simple: The image is inverted in the
camera, so the top-to-bottom traveling shutter slit exposes the image from
bottom to top!
Faster shutters are better. The base speed
of the shutter is apparent from the flash sync speed. Typical range is
from 1/30th to 1/250th of a second. The cloth-shutter cameras with horizontally
traveling slit are specially bad.
This effect is one of the very few
real uses of a zoom lens in photography. This time exposure was first flash-lighted,
and then the lens was zoomed in, letting the image on the monitor imprint
for some time at the final zoom position.
Never mind Roberto writing spaghetti code
on a Commodore VIC-20. For the younger among you, I shall explain that
this was a well-known home computer of the 1980's, and sported a whopping
5 kilobyte of RAM, 3.5 of which were actually available to the user! A
black-and-white TV served as monitor. There was no storage device: You
wrote the program, used it, then lost it when switching off the computer!
A neighbor hung some colored lights
into a tree. I shot a photo of it and swirled the camera around a bit before
closing the shutter. The original looks great, but on screen the colors
look very washed out. Sorry.
Flash exposure followed by slow camera
motion during a candle-lit dinner.
Light effects in a disco
Same as above, this photo was made
by first flashing and then moving the camera to make the lights streak.
The wine was a bit strong...
The camera was left on the floor,
looking up, while letting a small lamp pendulum swing above.
This can be used both for artistic
effects and for technical purposes. A machine part made from clear plastic
is illuminated from behind through a polarizer. The camera looks through
a second polarizer, turned to a 90-degree angle to the first. No light
can pass straight through both filters, that's why the filter in the background
looks black. But the plastic rotates the polarization, depending on the
color of the light and on internal stresses in the material. This rotated
light can pass the second polarizer and becomes visible. You can actually
watch the stresses as you bend the piece!
An old photography book I have mentions
the Clayden effect as being still unexplained. Strong, quickly moving lights
will sometimes reverse on the photo. The book showed photos of sparks flying.
Most where white, but a few sparks were totally black. I suppose that what
I got on this photo is the same effect! I was photographing insects dancing
on the water, and only on one of the 10 photos I made I got these totally
saturated, white lines with sharply defined edges. The strong light was
provided by the sun reflecting on the water, and the motion by the water
itself. It's pretty logical that on reversal film the Clayden reversion
produces white instead of black streaks!
This is a very rare happening. I have
not been able to intentionally obtain the Clayden effect on any photo.
I had heard so often that slide films
of higher sensitivity than ISO 100 are bad. But I'm the kind of guy who
has to try things! So I bought a roll of ScotchChrome ISO 1000 slide film.
This is the shocking result! Nice, huh? Honest, this scan looks
very closely like the original!
This film is useless even for special
effects! Hey, some grain can look good, but too much is too much! And the
contrast and color saturation is so ridiculous that I wonder why
they make such film at all!
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