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The distance that ensures the maximum depth of field for a particular lens, camera and focal length combination.  Often estimated as “approximately one third of the distance into the frame” it can be calculated relatively easily.

Hyperfocal Distance

A distance so great that any object at that distance will be reproduced sharply if the lens is set at its infinity position (that is, one focal length from the film).


The international standard for representing light sensitivity.  Originally the emulsion sensitivity of the film as determined by the standards of the International Standards Organization.  In these standards, both arithmetic (ASA) and logarithmic (DIN) speed values are expressed in a single ISO term.  The higher the number, the greater the sensitivity, and vice versa.  A speed of ISO 200 is twice as sensitive as ISO 100, and half that of ISO 400 film.

ISO speed

A collar or hood at the front of a lens that keeps unwanted light from striking the lens and causing image flare.  May be attached or detachable, and should be sized to the particular lens to avoid vignetting.

Lens hood

The largest lens opening (smallest f number) at which a lens can be set.  A fast lens transmits more light and has a larger opening than a slow lens.  Determined by the maximum aperture of the lens in relation to its focal length; the "speed" of a lens is relative: a 400 mm lens with a maximum aperture of f/3.5 is considered extremely fast, while a 28mm f/3.5 lens is thought to be relatively slow.

Lens speed

A lens that provides continuous focusing from infinity to extreme close-ups, often to a reproduction ratio of 1:2 (half life-size) or 1:1 (life-size).

Macro lens

Ratio that express greatest possible on film magnifying power of the lens.  Used commonly on the macro setting of the zoom lenses, macro lens or with bellows.

Magnification ratio

Nikon’s name for a macro lens.  

Micro lens