Glossary of Terms

Sabattier effect – partial reversal of an image produced by brief exposure to light part-way through a normal development process.

Sampling – regularly repeated measurements of small parts of a larger construct, such as an image, made with a view to reconstituting the whole from the information collected. This is the key process in digitization.

Saturation – the richness or vividness of a colour. A poorly saturated colour approaches grey; a fully saturated colour cannot be made more vivid. Colour is characterized by hue, saturation and lightness.

Scanner – device for digitizing film-based images (film scanner) or paper-based images (flat bed scanner).

Scrim – an attachment designed to be placed in front of a light source to reduce the intensity of its output.

Second-generation image – an analogue image created from a first-generation or original analogue image, and consequently of slightly lower quality eg a print made from a negative or transparency. Copied digital images are generally identical and hence free from generational decay.

Sharpness – a rather subjective quality attributed to images displaying good contrast, and clear and distinct reproduction of detail.

Shift lens – see perspective control (PC) lens.

Shutter lag – the period between pressing the shutter release and the moment the shutter opens, particularly in a digital camera.

Shutter priority - an autoexposure mode that allows the user to select a particular shutter speed manually and leaves the camera to select a corresponding aperture.

Shutter speed – in general, the period of time during which the blades of a shutter expose a film or sensor to light.

Silica gel – a highly absorbent compound, usually white granules, used to reduce humidity. It is commonly placed in sealed bags containing equipment or film to keep the air dry.

Skylight filter – a filter that absorbs ultraviolet and a little blue light. Used to remove ultraviolet haze and improves the contrast of a distant scene.

Slide – a mounted transparency suitable for projection. Colour reversal film is therefore commonly known as “slide film”.

SLR – a single-lens reflex camera featuring a single interchangeable lens through which, via a mirror and perhaps a pentaprism, a photographer is able to view an image. The mirror flips out of the light path to reveal the film or image sensor when the shutter is released.

Solarization – broadly, the reversal of tones apparent in grossly over-exposed images (such as those of the sun).

Spot-meter – an exposure meter that measures reflected light from a very restricted field of view eg 1^o. It has a viewfinder to facilitate accurate alignment, and a small telescope to channel light to the sensor.

Standard lens – a lens having a focal length approximately equal to the diagonal of the camera’s film format, or a field of view comparable with that of the human eye ie about 45^o.

Storage media – devices designed to hold digital data typically from a computer or digital camera – eg CompactFlash card or DVD.

Strobe – an electronic flash unit usually capable of producing rapidly repeating flashes.

Sync speed – the fastest shutter speed with which flash output is fully synchronised with the period of exposure.

Synchronization (sync) – the process of ensuring that separate events happen at the same time eg an electronic flashgun fires after a shutter has opened and before it has closed.