Canon EOS D30 User Manual download pdf (Page 130)

130

REFERENCE

Basic Terminology for Digital Cameras and

Digital Photography

Auto Exposure is a function that calculates the exposure automatically. The camera has a built-

in exposure meter that automatically determines the correct exposure (the combination of

shutter speed and aperture value).

Auto Focus is a function that focuses the camera automatically.

Aperture value

The lens aperture opens and closes to control the amount

of light that reaches the imaging element. The aperture

value (or f-number) is equal to the focal length divided by

the aperture diameter. The aperture value is displayed on

the camera’s LCD panel and in the viewfinder, and ranges

from 1.0 to 91, depending on the particular lens mounted

on the camera.

CF (CompactFlash) Card

CompactFlash card is the storage media used to record photo images taken by the EOS D30.

Depth of Field

When a subject is in focus, a distance in front of and behind the subject is also in focus. This

is called the depth of field. The greater the aperture value (that is, the smaller the aperture),

the broader the depth of the field. This is called a deeper depth of field. Conversely, the smaller

the aperture value (larger aperture), the narrower the depth of field, called a shallower depth

of field.

The depth of field is affected as described below:

q A smaller aperture (larger aperture value) increases the depth of field.

Thus, reducing the aperture provides a deeper depth of field.

w At a given subject distance and aperture value, a lens with a shorter focal length increases

the depth of field.

Thus, a wide-angle lens gives a deeper depth of field than does a telephoto lens.

e At a given aperture value, a greater distance between the camera and subject increases

the depth of field.

r When the optimum focus is on the subject, the depth of field behind the point of optimum

focus is longer than the depth of field in front of the point of optimum focus. The depth of

field is normally twice as deep behind the subject as before the subject (see illustration).

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Canon EOS D30 User Manual Page 130