Cameras have gone through many changes in instrument. The eye has a lens, and like the lens of a design over the years. Several of your chiefs and camera, it forms an image on a light-sensitive surface division officers remember lugging around bulky, (fig. 4-1). The lens of the eye focuses light on the retina. cumbersome 4x5 Speed Graphic cameras with film The camera lens focuses light on the film plane. The lens holders and tripods just to cover routine assignments. of the eye focuses by changing its curvature, the camera Through the development of modern-day cameras and lens by changing its focal length. The diaphragm on a film, small, hand-held cameras are commonly used. A camera is similar, like the iris of the eye. When the light large variety of cameras are available in the imaging is bright, the iris closes down, reducing the brightness

facilities of the Navy. After learning the nature of your of the image. Likewise, when the light is bright, the assignment and the equipment available, you must camera diaphragm closes down When the light is dim,

choose the equipment that will get the job done best, the diaphragm opens up. The components of the eye are

whether it be a 4x5 view camera or a small, hand-held held together by the sclera, the components of the electronic camera. camera by the camera body.

The human eye may be compared to a camera There A camera in its simplest form (fig. 4-2) is a lighttight are several similarities. The eye is a physiological box with a lens to form an image, a shutter to control the optical instrument. The camera is a mechanical optical length of time light is allowed to act on the film, a

Figure 4-1. Comparison of human eye to a camera.

Figure 4-2. A simple camera.

R. B. Burrows

Figure 4-3. 35mm single-lens reflex (SLR) camera.

diaphragm to control the brightness of the image, a means of holding the film at the back of the camera, and a viewfinder so the photographer knows what the image is, and of course a body to hold it all together.

Simple cameras, such as the one described, have limited capabilities. They have a fixed-focus lens that cannot produce a sharp image of a subject closer than about 6 feet. Also, the shutter speed and diaphragm are preset and cannot be altered. The capabilities of a simple camera can be enhanced by adding features to perform the following:

Focus on subjects at various distances

Adjust the lens for different lighting conditions

Change various lenses quickly to change focal length and fields of view

Change shutter speed to capture images of moving subjects

Use synchronized electronic flash

Meter the image brightness of the subject to either manually or automatically adjust the diaphragm and shutter speed

Figure 4-3 illustrates a common 35mm camera and identifies the various camera controls.