Figure 11-4.The basic principle of a 35mm SLR camera.
Modern SLR cameras accept a vast assortment of
lenses, ranging from fisheye to extreme long-focus types.
With their interchangeability of lenses, film backs and
other accessories (such as electronic flash attachments),
SLRs can more aptly be called camera systems.
Lenses are usually attached to the camera by a
bayonet flange. Focusing is done by turning the lens
focusing ring. A screw thread, which runs around the
inside of the lens barrel, moves the lens closer or farther
away from the film, as the focusing ring is turned.
Most SLR camera lenses have an iris diaphragm.
This diaphragm is held at full aperture for focusing and
viewing and is stopped down automatically to the preset
working aperture at the instant of exposure. This means
that while the image on the viewing screen is bright and
easy to see, only the connect amount of light reaches the
film for exposure.
Your SLR camera will have a built-in exposure
meter that usually reads through the lens (TTL). The
meter may measure the light falling on the minor, the
focusing screen, or in some models, even on the film at
the instant of exposure. On an automatic camera, the
meter even adjusts the aperture or shutter speed to give
the correct exposure. On manual cameras the meter
produces a display in the viewfinder to indicate the
correct exposure. The user then sets the camera controls
to get the correct exposure.
Almost all SLRs have final-plane shutters. They
simplify the construction of the camera and make the
use of interchangeable lenses easier. The shutter,
aperture and mirror all work together in a precise
sequence, repeated each time a picture is taken.
The relatively small size, ease and speed of
operation, reliability and the high quality of photographs
of the SLR cameras have combined to make it a favorite
of professional photographers and photojournalists.
CONTROLS AND INDICATORS
In the Navy, most photojournalists are issued a
camera kit that consists of a Canon F-1 35mm SLR
camera, a 50mm lens, a 35mm lens, a 135mm lens and
a flash unit. This camera is shown in figure 11-2.
Some of the main controls and indicators of the
35mm SLR camera are covered in the following text.
Film Advance Lever
The film advance lever advances the film one frame
at a time, cocks the shutter, prepares the aperture and
mirror for exposure and advances the frame counter one