How well do you understand your camera?

The camera is an instrument used to take pictures and make movies. It is one of the most important means of communication, documentation and expression.

All cameras use the same basic principles to form an image. Light reflects off the scene being photographed and strikes the camera lens. Light passes through the lens and forms an inverted (upside down) image on the back of the film. The image can be focused by adjusting the distance between the lens and the film. Most have a focus mechanism whereby the photographer moves the lens a short distance to focus the image. Others will automatically adjust this distance by means of a focusing mechanism that is sensitive to light, infrared rays, or sound waves.

A device called a shutter opens to allow light into the camera. The shutter can be behind the lens, between two lenses, or directly in front of the film. The speed of opening and closing the shutter determines how long the film is exposed to light. By opening and closing rapidly, the shutter can “freeze” a moving image. Many cameras have adjustable shutter speeds, ranging from 30 seconds to 1/2000th of a second, but some have electronic shutters that adjust speeds automatically.

A device called an iris is placed in front of, behind, or inside the lens and controls the amount of light that enters. The diaphragm can expand on a cloudy day to let in more light or contract on a sunny day to let in less light. Most cameras have an electric eyepiece mechanism that measures light intensity and automatically adjusts the aperture.

Types of cameras

fixed focus cameras, the most basic and has a non-adjustable lens. Most models have a single aperture setting and only one or two shutter speeds. Most fixed focus cameras use 110 or 126 size film. This can take satisfactory pictures in normal daylight but not in dim light, because its lens doesn’t admit a lot of light.

point and shoot cameras they have many automatic features that make them easy to use. Internal electronics will automatically adjust focus, set light exposure and shutter speed, and advance film rewind. A built-in electronic flash automatically provides light when very little light is reflected on the subject. It is equipped with high-quality lenses that produce a sharp image. Some of them have a zoom lens.

single lens reflex cameras appeal to both expert amateur photographers and professional photographers. The photographer views the subject through the lens rather than through a separate viewing lens. A mirror between the lens and the film reflects the image onto a viewing screen. When the shutter button is pressed to take a photo, the mirror flips up to allow light to expose the film. Thus, the photographer sees almost the exact image that is recorded on the film.

twin lens reflex cameras have a viewing lens directly above the picture taking lens. The image in the viewfinder appears on a flat screen at the top. Photographers usually hold it at their chest or waist and look down into the viewfinder. The image appears inverted from left to right.

see cameras they are the largest and most adjustable type. Most of them have an accordion-like body, with a replaceable lens in front. They have a large display screen instead of a viewfinder. It must be mounted on a stand for effective operation and can provide artistic distortion of a subject more effectively than any other type of camera.

instant cameras use the film that provides a print without first developing it on a negative. Produces a print 15 seconds to 2 minutes after the photographer takes a photo. The time varies depending on the camera and the type of film. Sometime you can take flash pictures and autofocus when the photographer lines up a subject in the viewfinder.

digital cameras create images that can be viewed on a television screen. The bulk of the lens focuses light onto a light-sensitive mechanism called a charge-coupled device (CCD). The CCD transforms light into electronic signals. Electronic images can be stored on small magnetic disks similar to those used in computers.

film cameras take pictures that recreate the movement of a subject when viewed. Professional filmmakers generally use large cameras that take 35- or 16-millimeter film. Today many amateur filmmakers use camcorders.

stereo cameras have two identical lenses to take pictures with combined shutters. When you take a photo, each lens photographs the same subject, but from a slightly different angle. When displayed in a device called a stereoscope or viewed through light-polarizing lenses, the two images blend into one image that appears to have depth. It is made for taking pictures or making movies.

Special cameras have been designed for industrial, medical, military and scientific uses. They include aerial cameras used in space and underwater cameras.