Gr selecting a shutter speed, G. selecting a shutter speed -29 – Canon EF User Manual

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at the "NORMAL'' position.

* If the preceeding discussion seems complex, keep

in mind the following definitions:

An f/stop is a number used to represent the amount

of light which is allowed to pass through the lens.

The diaphragm is the mechanical iris inside the lens

which is opened or closed according to the setting of

the aperture ring.

The aperture is the hole or opening formed by the

diaphragm blades.

Gr Selecting a Shutter Speed

The

amount

of light striking the film is controlled by

the lens diaphram, whereas the

length of time

that

light is allowed to strike the film is controlled by the

focal plane shutter. The shutter consists of two

opaque "curtains" which travel over the opening and

allow the light coming through the lens to reach the

film. The length of time the curtains remain open

determines the exposure time for your picture. On
the shutter speed dial, shutter speeds from 1/1000 —

1 sec., and B, are marked in white (with the

exception of the orange "125" for electronic flash

synchronization), while the speeds from 2 — 30

seconds are marked in yellow. To set the shutter

speed, rotate the dial in either direction until the

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