Safelight

A red or orange darkroom light that black and white photo papers aren't sensitive too.

Saturation

Relative richness of colors in a color image.

SCSI

Small Computer System Interface. A computer interface used for digital imaging as it is both high speed and standard.

Selective Focus

Employing wide apertures to produce shallow depth of field so that the subject is isolated from its surroundings as they will be not in focus.

Selenium Cell

A light sensitive electronic device that emits electricity in proportion to the amount of light falling on it. Used for light meters.

Self Timer

Mechanism that delays the shutter action after being actioned. Useful both to allow for the photographer to be included in the image and as means to reduce camera shake from shutter button jerking.

Separations

Black and white negatives that separate the continuous colors of an image into two to four colors for offset printing. The most common separations are for CMYK, or cyan, magenta, yellow and black.

Sharpness

The amount of detail that can be perceived in an image. Definition of an image in terms of focus and contrast. The combination of resolution -typically measured in terms of the number of distinguishable line pairs per millimeter- and acutance -the power to resolve detail in the transition of edges.

Sheet Film

Film that is cut into individual sheets. Mostly comes in 4x5 or larger sheets.

Sheimpflug Principle

Geometric rule which affects correct focus of view cameras with tilt-shift movements. Three planes are of concern when focusing a view camera: that of the image (at the film/sensor), the lens plane and the subject plane. If these three planes are precisely parallel to one another then a focused image will appear sharp across the entire image area. Tilting one of these planes will result in the area in focus changing. The image area will be in focus only at the point where the three planes intersect. Although the French builder of scientific instruments Jules Carpentier (1851-1921) was the first to enunciate it, the rule is named after Austrian army officer Theodor Scheimpflug (1865-1911).

Shutter

The mechanical device in a camera that controls the amount of time light is allowed to reach the film.

Shutter Priority

A camera exposure mode that allows the photographer to choose a shutter speed while an electronic processor in the camera sets a corresponding aperture for best exposure.

Single-Servo AF

When the subject comes into focus, the focus operation stops and stays locked as long as the shutter release button is lightly pressed. Used when shooting stationary objects.

Silver Halide

The light sensitive component in treated photosensitive surfaces.

Silver Nitrate

Chemical found in photo developers and used in treated photosensitive surfaces.

Single Lens Reflex (SLR) Camera

A camera that uses a mirror and prism to allow the photographer to see through its single lens.

Skylight Filter

Filter used to remove more UV light (and therefore excessive blue) than a UV filter, adding a slight warming tone in two grades: 1A and 1B, where be is the warmer one.

Slave

A light sensitive trigger device used to synch strobes and flashes without an electronic synch cord.

Slide

A transparency mounted in a square paper or plastic frame. (Not just 35mm)

Slow Sync

Setting allowing for slower shutter speeds while using flash, usually for more illuminated backgrounds.

Snapshot

A quick casual image, typically taken handheld by an amateur with a Point & Shoot camera.

Soft-Focus

An effect achieved by diffusing an image either in the camera or printing stage. Can be done with special lenses or by placing diffusion devices or materials between the light source and the light-sensitive material. Mostly used for portraits but not exclusively.

Soft Lighting

Low contrast illumination, allowing for more pleasing portraits; without harsh contrast.

Solarization

Also known as the Sabbatier effect. Usually achieved by exposing a developing image to white light during the development process. The effect is a partial reversal of the image.

Spectrum

The visible separation of light into colored bands as white light passes through a prism.

Speed

In photography, the sensitivity of a photosensitive material. This is expressed as either an ASA, ISO or DIN number.

Spherical Aberration

A lens fault which results in degraded image quality at the film plane. It is caused by light rays passing through the lens from a single point on the optical axis focused at different points according to incident height. Spherical aberration can be reduced by stopping down the lens.

Split Image Rangefinder

Two prisms with faces angled in opposite directions and used to aid in focusing. A subject will appear split, even with slightly out-of-focus, allowing a photographer to adjust for accurate focus.

Spot Meter

A light meter, which takes it's reading at an angle of 1 to 8 degrees. Used for the zone system or to find the values of specific elements in a scene.

Spotting

Retouching dust spots or other fine blemishes in a photographic image with a small brush. Usually only done on prints.

Standard Lens

Refer to "Normal Lens."

Stereoscopy

Photography that uses two images taken from slightly different angles to produce the illusion of three dimensions when seen through a special viewing device.

Stopping Down

To decrease the size of aperture in a lens, e.g., to stop down from f/3.5 to f/16. Increases depth of field, requires longer exposure.

Swing

A view camera movement used to control depth-of-field and perspective. Allows the angle relation of the film plane and lens to be changed from side-to-side.