Pieces of Science

The Story

For Teachers

For Students

For Reference

Types of Cameras

and Light Characteristics

Type of Cameras

We classify cameras into four groups by the way they are focused. Rangefinder and viewfinder cameras have a "viewfinder" through which the picture is framed. The rangefinder differs from the viewfinder in that it has a double image created through the use of mirrors. We refer to this as a split-image. When the two images line up (are superimposed) the camera is in focus.

Twin Lens cameras have two look-alike lenses, hence the name "twin lens." The scene before the camera is actually photographed through the bottom lens while viewed through the top lens. As the picture is focused through the top lens, the bottom lens is adjusted at the same time.

The Bellows camera gets its name from the characteristic bellows. The bellows are the accordianlike body that connects the lens to the rest of the camera. But it is important to remember that it is focused on the ground (frosted) glass at the back of the camera, before the film pack (or plate) is inserted. (Not all cameras with bellows are classified as "bellows" cameras. Incidentally, these cameras may also be referred to as view cameras, not to be confused with the viewfinder type listed above.)

The Single Lens Reflex (SLR) uses a series of mirrors so that one may view the scene to be photographed through the same lens that takes the picture. When the shutter release is depressed the lower mirror snaps up, the picture is taken, and the mirror returns to its original position. (Hence, a "reflex" action.) At the time the picture is taken, the viewfinder is blackened for a split second.

Light characteristics

Light travels in a straight line and, when white, represents the presence of all colors. We call light direct from the source incidence light, while indirect light is referred to as reflected light. Some light meters have two settings depending on the lighting situation. Can you think of some examples of each type? Since light travels in a straight line, we find that in the eye, or in a simple pinhole camera, the image will appear upside down and backwards.