Apple Aperture Digital Photography Fundamentals - Manual (Page 13)

Chapter 1 How Digital Cameras Capture Images 13
Lens Types
Although there are many varieties of lenses, common lens types include telephoto, wide-
angle, zoom, and prime. All of these lenses perform the same basic function: they
capture the reflective light from the subject and focus it on the image sensor. However,
the way they transmit the light differs.
Note: Although there are several subcategories and hybrids of these lens types, these
are the most basic.
Telephoto
A telephoto lens is a lens with a long focal length that magnifies the subject. Telephoto
lenses are typically used by sports and nature photographers who shoot their subjects
from great distances. Telephoto lenses are also used by photographers who want
greater control over limiting the depth of field (the area of an image in focus). The
larger aperture settings, combined with the long focal lengths of telephoto lenses, can
limit the depth of field to a small area (either the foreground, middle, or background of
the image). Small aperture settings, combined with long focal lengths, make objects in
the foreground and background seem closer together.
Wide-Angle
A wide-angle lens is a lens with a short focal length that takes in a wide view. Wide-
angle lenses are typically used when the subject is in the extreme foreground and the
photographer wants the background in focus as well. Traditionally, the focal length of a
wide-angle lens is smaller than the image plane. However, in the digital photography
age, the sizes of image sensors vary, and the lens multiplication factors of most DSLRs
increase the focal length. Check the specifications of your camera to ascertain the size
of your digital image sensor. If the size of your digital image sensor is 28 mm, you
require a lens with a focal length less than 28 mm to achieve a wide-angle view.