THE PHOTOGRAPHIC EYE

EXERCISE
Testing the Shutter & Aperture
By now you should be familiar with
all the components that have an effect
on the shutter. Let's take a look
at them all in action.
Set your shutter speed to "B" and
your lens to its largest aperture
(remember, that's the lowest
number). Make sure the film advance
lever has been wound, to cock the
shutter. Open your camera back.
Aim the lens at any convenient light
source. While looking at the shutter
screen, press the shutter release button
and hold it down.
You should find yourself looking
through a hole about the size of a
quarter, through which you'll be able
to see whatever's in front of your
lens . . . except everything will be upside
down and probably out of focus.
48 The Photographic Eye
Let the shutter close and then cock
it again. Set your lens to its smallest
aperture (the highest number). Look
through again and press the shutter
release.
This time you should see a much
smaller hole, with five or more sides.
The hole gets its shape from overlapping
metal plates in the lens. The
plates come closer together as the
aperture decreases, and they spread
further apart as the aperture
increases.
Set the lens to its largest aperture
again. Cock the shutter and set the
shutter speed to 60. Click and watch
again. Try the same thing at 125. Try
it at 30. Can you tell them apart?
Move up and down the shutter speed
dial to get a sense of how the speeds
differ.
Do the same thing with all the different
apertures with the shutter set
at "B," so you can see the different
sized openings.
Now close the back of the camera
and remove the lens. Set it aside
where it will be safe. Look into the
camera from the front. If you have
an SLR (or Single-Lens Reflex)
camera, you should see a mirror set
at an angle. Above the mirror you'll
see the focusing screen. If you look
very carefully, you may also be able
to make out some of the other
displays you saw in the viewfinder.
The triangle on the camera's top is a
prism that "bends" the image of the
focusing screen around to the viewfinder
so you can see it.
Aim the back of the camera
toward a light source and look into
the mirror. You should be able to see
out through the viewfinder, though
most everything will be blurry.
With the shutter speed still set at
"B," cock the shutter. Press the shutter
release and notice how the mirror
swings up out of sight. The black rectangle
you see at the back is the metal
plate that holds the film in place. Let
go of the shutter release and you'll see
that the mirror drops right back into
place. Now try the same thing at your
camera's fastest shutter speed.
That concludes the testing exercises.
Now it's time to do it all for
real.