Glossary of Terms

Macro lens – a lens whose design has been optimized for close-up work, with a maximum reproduction ratio of about 1:1.

Magnification – the ratio of the size of an image of an object to the physical size of the object. It is sometimes known as reproduction ratio.

Megabyte (MB) –one million bytes of computer data.

Megapixel (MP) – one million pixels. The unit is commonly used as a unit of the capacity, or resolution, of a sensor in a digital camera.

Metadata – data used to describe other data, typically intellectual content information recorded about an image to enhance accessibility.

Mid-tone – a tonal value midway between white and black. 50% grey or a value of 128 on an 8-bit scale.

Mired – micro-reciprocal degree; a measure of colour temperature of a light quoted as the reciprocal of the colour temperature multiplied by one million. Colour correction filters commonly have “mired shift” values.

Mirror lens – a relatively compact lens that utilizes curved mirrors to form an image.

Monitor calibration – calibration of the colours displayed by a computer’s monitor using a colorimeter. This is an essential part of colour management.

Monochrome – strictly, an image consisting only of white, black and numerous greys. Tinted images based on any single hue may also be described as monochrome.

Motor-drive – motorized camera system designed to automate film transport and rewind, and cocking of the shutter.

Multiple exposure – a method used to combine several images on a single frame of film or in a single digital image.

Multi-segment (matrix) metering - exposure determination system commonly found in SLRs based upon separate measurement of brightness in at least five discrete areas of a scene; typically four quarters and a reserved central area.