Film format. It's name referring to the size of the negative produced

When light falls on an object some of it is absorbed by the object and is usually converted to heat. The remainder either passes through the object or is reflected from it. The overall proportion of t [..]

A ray of light falling on a surface forms an angle with an imaginary line drawn at right angles to the surface. The imaginary line is known as the normal and the angle between it and the incident ray [..]

A ray of light reflected from a surface forms an angle with an imaginary line drawn at right angles to the surface. The imaginary line is known as the normal and the angle between it and the reflected [..]

The maximum angle between rays of light passing through the lens from those parts of the subject which will just be included within the picture format. Usually quoted as the angle given by the diagona [..]

Hole positioned concentrically with the optical axis of a lens to restrict the area of the lens through which light can pass. Usually adjustable in size, formed by an iris diaphragm. Main purpose is t [..]

Initials standing for Advanced Photo System. Using a negative of 26mm but storing data along side the photo for developing proposes.

Illumination other than natural daylight. The main sources of artificial light for photographic use are tungsten lamps, flashbulbs and electronic flash.

The American Standards Association rating of film speed (sensitivity of the emulsion to light). The scale is a simple arithmetical progression, double the ASA number indicating twice the film speed. T [..]

Hinged flaps fitted to photographic flood and spot lights to control the width and direction of their light beam.