Camera
A camera is little more than a light-tight box containing some image recording media (usually film or digital sensor) with a shutter to control exposure of that media to light.
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Anatomy of a Camera
Back
Some cameras - especially medium format and large format cameras - have interchangeable backs. Different backs allow you to continue shooting without having to rewind and reload film. They also make it possible to use different film formats. Some cameras have backs available for everything from 35mm to 6x6 to 8x10 film.
Frame Counter
A frame counter is a mechanism for recording the number of film frames exposed or for calculating the number of exposures remaining on a roll of film or memory card.
Shutter
The shutter is the mechanism that opens and closes at specified intervals in order to allow light to pass through the lens. The two most common types of shutter are leaf shutter and focal plane shutter.
Viewfinder
The viewfinder is the part of the camera that indicates, either optically or electronically, what will appear in the field of view of the lens. In most cases this is a glass window you look through to compose, but in some cases in can be as simple as one or more wire frames you use to approximate your field of view. Many of today's point-and-shoot digicams have omitted the optical viewfinder and use an LCD screen on the back of the camera as its viewfinder.
A diopter adjustment is an optical adjustment on the viewfinder of a camera that allows someone to adjust the viewfinder's magnification to their vision, removing the need to wear eyeglasses when looking through it. Diopter adjustments cannot compensate for all vision problems, only near and far sightedness can be compensated.
TTL Metering
TTL or through the lens metering is a method of metering in which a camera's built-in light meter reads the light coming through the lens. This is considered to be more accurate because the light meter only sees the light that will hit the focal plane and other ambient light conditions can't "fool" the meter.
Autoexposure
Cameras with auto-exposure are able to set the shutter speed, the aperture, or both automatically based on the meter reading.
Center-Weighted
Center-weighted light-meters favor the center of the frame, while taking into account the rest of the frame to a lesser extent.
Autofocus
Autofocus cameras are able to adjust the lens electronically in order to get your desired subject "in focus".
Parallax
Parallax is an effect in photography where the image seen in the viewfinder is not framed the same as the image seen through the lens. This effect is most noticeable with subjects close to the camera, and becomes relatively insignificant at longer distances. All cameras with separate viewfinder and taking lens suffer to some degree from parallax error. Cameras which view the scene through the taking lens, like SLRs, don't have parallax problems. Some cameras with separate viewfinder and lens have some form of parallax correction.
