Acetal Homopolymer. Engineering plastic with sufficient hardness and dimensional stability for the manufacture of precision components (e.g., screw-threads). Depth of field:

Single-lens semi-transparent-mirror reflex camera (SLR in which the mirror stays in place during shooting). Sn

A

'acrylonitrile-butadiene-styrene co-polymer' - a cross between plastic and rubber with excellent engineering properties, used to make underwater housings, cabinets for electronic equipment, solvent-weld plumbing fittings, etc.. ABS is attacked by many industrial cleaning agents, especially chlorinated solvents, ketones (e.g., MEK), and fu [..]

Alternating current. An electrical current which changes over time, usually in a sinusoidal fashion. Usually associated with mains electricity.      When Thomas Edison an his co-workers developed electrical lighting into a commercially practical technology, the original power distribution system used direct current

a lens corrected for chromatic aberration (colour fringing) at two wavelengths in the visible spectrum. Most modern camera lenses are achromats. Achromatic doublet:

Automatic Exposure. A method of linking the camera exposure settings to the ambient or reflected light level. AF:

The capacity rating of an electrical cell or battery. One point to watch when interpreting ampere-hour ratings is that the capacity of a battery or cell varies depending on the rate of discharge. The figure is normally specified at the 10 hour rate. E.g., A 10Ah battery will deliver a current of 1 amp for 10 hours. It will however, deliver a curren [..]

The unit of electrical current, ie., quantity of electricity per unit time. Current flows through

The angle between rays of light entering a lens from the extreme corners of a scene. Angle of Coverage (of a flash unit):