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 number.

Shutter Release Button

The shutter release button opens the shutter and initiates the exposure.

Shutter Speed Dial

The shutter speed dial indicates optional shutter speeds and sets the length of time the shutter remains open during an exposure. Shutter speeds are indicated in fractions of a second; for example, 60 = 1/60 of a second (also expressed as 1/60"). The higher the number on the dial, the faster the shutter speed and the shorter the exposure.

ISO Indicator

The ISO (International Standards Organization) indicator allows you to compensate for the particular "speed" of your film. For example, if you are shooting black-and-white film with an ISO of 400, you will set your ISO indicator to 400. The higher the ISO, the more light sensitive the film.

Aperture Control

The aperture control is a ring around the lens with a scale listing aperture numbers (2.8, 3.5, 4, 5.6, etc.). These numbers are also known as "f/stops." The ring sets the f/stop on the lens to control the amount of light entering the lens.

Film Rewind Knob

The film rewind knob is used to rewind the film into the cassette (film canister), to tighten slack in loaded film and to open the back of the camera. You turn the knob in the direction of the arrow to rewind the film, and lift it to open the back of the camera.

LENSES AND APERTURES

As noted previously, most 35mm SLRs have interchangeable lenses. The "final length" of a lens is the distance from the optical center of the lens to the final plane (film plane) when the camera is focused upon an object at itifinity. A 50mm final-length lens is considered the "normal" lens because when you look through the viewfinder, objects appear at their approximate normal size. A smaller than normal focal length (such as 28mm) means a wider angle of view. A longer than normal final length (such as 135mm) is a telephoto lens. Focal length affects film image size.

Figure 11-5. - Comparison of the iris diaphragm of a cameralens to the iris of the human eye.

The f/stop (aperture) ring controls the amount of light passing through the iris diaphragm of the lens and striking the film. The higher the f/stop number, the smaller the amount of light allowed to enter the camera lens. This principle works in the same manner as the iris of the human eye (fig. 11-5).