Canon A-1 - Manual (Page 32)

The length of time that the light is allowed
to strike the film is determined by the
shutter speed. The relationship between
shutter speeds is like that between f/stops.
As you move from one shutter speed to the
next higher shutter speed, exposure is
halved. Your image is actually exposed by
the opening of the shutter. Shutter speed
can be controlled on the A-1 by turning the
AT dial. Otherwise the camera controls it.
Now suppose that you have the camera set
for a certain exposure value (EV), say the
exposure you get with f/4 at 1/60 sec. There
are certain other combinations of aperture
and shutter speed which will give you the
same amount of exposure as that above.
Some of these combinations in this example
include f/5.6 at 1/30 sec. and f/2.8 at 1/125
sec. You simply move up and down the
f/number and shutter speed scales. It is not
important to know this relationship when
you use the A-1 in an AE mode. The camera
will do the figuring for you. But it is an im-
portant photographic fact which you may
find useful when you use the camera
manually or in correcting exposure.
AE Photography
AE photography means automatic exposure.
The camera is selecting either shutter speed
or aperture or both for you.
The most obvious, unusual feature of this
camera is the absence of the shutter speed
dial which has been replaced by the AT dial.
This dial allows you to set either shutter
speed or aperture for any of five different
AE modes.
Through-the-lens full-aperture metering
Shutter priority AE
Aperture priority AE
Programmed AE
AE flash photography
Through-the-lens stopped-down metering
Stopped-down AE
In shutter-speed priority AE, you set the
shutter speed, and the camera automatically
selects the necessary aperture according to
lighting conditions for correct exposure.
Shutter-speed priority AE, is applicable to
most subjects but especially useful in action
photography.
In aperture priority AE, you set the aperture
while the camera automatically selects the
necessary shutter speed for correct exposure.
It is convenient for the various forms of still
photography in which depth of field is of
importance.
The camera automatically selects both
Not For Resale – Free Download at http://www.joe-chan.com/manuals
–32–