A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Falloff - Decrease in the intensity of light as it spreads out from the source.

Fast film - High speed film, i.e. film that is more sensitive to light, meaning less light is needed to obtain a properly-exposed image.

Fast lens - A lens of wide maximum aperture, rela­tive to its focal length, allowing maximum light into the camera in minimum time, The speed of a lens - its relative ability to take in light - is an important measure of its optical efficiency: fast lenses are more diffi­cult to design and manufacture than slow lenses, and consequently cost more.

Field camera - A type of camera known as the "field" or "baseboard" camera is essentially a portable view camera, because it functions in much the same way and with similar controls and features.

Fill flash - Flash that is used in a supplementary manner to fill in a subject’s shadow area with light, thereby reducing contrast. Also known as “flash fill” and “fill-in flash.”

Fill-in light - Additional lighting used to supplement the principal light source and brighten shadows. Fill-in light may be supplied by redirecting light with a card reflector or by using a flash unit, for example.

Film - A transparent cellulose nitrate or cellulose actetate composition made in thin, flexible strips or sheets and coated with a light-sensitive emulsion for taking photographs.

Film plane - The place in a camera where the film is located in readiness for it to be exposed to light.

Film solarization - See "Solarization" in this Glossary.

Film speed - A film’s sensitivity to light, rated numerically so that it can be matched to the camera's exposure controls. The two most commonly used scales, ASA (American Standards Association) and DIN (Deutsche Industrie Norm), are now superseded by the system known as ISO (International Standards Organization). ASA 100(21° DIN) is expressed as ISO 100/21° or simply ISO 100.

Filter - A thin sheet of glass, plastic or gelatin placed in front of the camera's Pens to control or change the appearance of the picture. Some filters affect color or tone; others can, for example, cut out unwanted reflections, help to reduce haze or be used to create a variety of special effects.

Filter factor - A number that indicates to what extent you must increase exposure when you use a particular filter (by multiplying the unfiltered exposure by the filter factor number). Filters absorb light. The filter factor allows you to compensate for this absorption. The amount of exposure compensation has been predetermined for every filter, and is expressed as a “filter factor” (sometimes also called an exposure factor, and also referred to as Exposure Magnification or EM values).

Filter size - is determined by the inner diameter of the front of a lens, more specifically the threads into which a filter is screwed to attach it to the lens. A 62 mm filter screws onto a lens that has threads that have a diameter of 62 mm. Most filters and some lenses are inscribed with their filter size in millimeters.

Filtration - In color printing, the use of filters to control the colors of the enlarged image and thus of the final print

Fine grain developers - Film developers that minimize grain in the final image.

Finder - A shorter word to use when referring to a camera’s viewfinder.

Fisheye - Describes an extreme wide-angle lens that has an angle of view exceeding 100° - sometimes more than 180° - and that renders a scene as highly distorted.

Fixation - In negatives and prints alike, the conversion of unused silver halides to a soluble silver so that the image remains stable and unalterable when exposed to light. Also known as “fixing.”

Fixed focal length  - Descriptive of the lens in a camera that has one lens only that cannot be interchanged for another lens and that cannot be zoomed.

Fixed focus - Refers to a lens, the focus of which cannot be changed. Found in simple cameras, the focus is preset (or fixed) by the factory, usually at the hyperfocal distance, resulting in image sharpness for most common shooting conditions for snapshots.

Fixer - A chemical bath used to make a photographic image stable after it has been developed. The fixer stabilizes the emul­sion by converting the undeveloped silver halides into water-soluble compounds, which can then be dissolved away.

Flagging the light - To some extent, a Barn-door on the reflector or a louver in front of the soft-box can be used to round off the lighting edge. For a sharp, distinct lighting edge, a flag will have to be placed at a distance from the light source, close to the subject.

Flare - Light that doesn’t belong in an image, often taking the shape of the aperture, generally caused by shooting towards the light source. The source may appear in the image as a reflection from the interior of the camera or from the lens. Flare often results in an overall reduction of image contrast.

Flash - A very brief but intense burst of artificial light, used in photography as a supple­ment or alternative to any existing light in a scene. Flash sources take various forms. Some small cameras have built-in flash, but for SLRs the most popular flash units slot into the top of the camera.

Flash bulb - A one-time-use glass bulb enclosing a pyrotechnic wire filament that burns out, generating a bright flash, when an electrical current is run through it.

Flash cube - A cube-shaped unit containing four built-in flash bulbs that automatically rotates to the next usable bulb when one is fired. When all four flash bulbs have been fired, the unit is no longer usable, and is discarded. The flash cube is now obsolete, but was at one time a common flash accessory for many point-and-shoot cameras.

Flash Duration - According to the international standard, the time from flash-tube igniting up to a specified point (t0,5), at which the light is no longer considered to affect the exposure.

Flash Factor - Also known as " Guide number," a number which serves as a guide to proper exposure when using flash. The number is based on a flash unit's light output and the film speed. When the flash factor is divided by the flash-to-subject distance, the correct aperture for proper exposure is determined. Flash factors may be quoted in meters or feet, according to which system is used for the measurement of distance.

Flash fill - Flash that is used in a supplementary manner to fill in a subject’s shadow area with light, thereby reducing contrast. Better known as “fill flash” or “fill-in flash.”

Flash meter - Exposure meter designed to measure the light from electronic flash.

Flash powder - Used in the early days of photography, a mixture of metallic magnesium with an oxidizing agent that, when ignited, produces a bright flash of light.

Flash synchronization  - Timing the triggering of the flash so that it fires only when the shutter is completely open, thereby ensuring complete exposure of the entire film frame.

Flash terminal - Electrical contact on a camera to which a cord that is connected to a flash unit is attached, permitting flash synchronization.

Flat - A negative, slide or print that is too low in contrast due to a limited range in density.

Flat lighting  - Illumination that provides little contrast on the subject and light or imperceptible shadows.

F-number - The number resulting when the focal length oaf lens is divided by the diameter of the aperture. A sequence of f-numbers calibrates the aperture in regular steps (known as stops) between the minimum and maximum openings of the lens. The f-numbers generally follow a standard sequence, in such a way that the interval between one full stop and the next represents a halving or doubling in the image brightness. The f-numbers become progressively higher as the aperture is reduced to allow in less light.

Floodlight - Continuous (non-flash), artificial light source, generally used in the studio for evenly-spread illumination. Also known as Photoflood or Flood lamp. Has a colour temperature of 3400° on the Kelvin scale.

ƒ-stop - (f-stop) A lens aperture setting calibrated to an f-number.

Focal length - The distance, usually given in millimeters, between the optical center of a lens and the point at which rays of light from objects at infinity are brought to focus. In general, the greater the focal length of a lens, the smaller and more magnified the part of the scene it includes in the picture frame. A standard lens for a 35mm camera typically has a focal length of 50mm, a wide-angle lens one of 28mm and a telephoto lens one of l35mm.

Focal plane - The plane on which the image of a subject is brought to focus behind a lens. To produce a sharp picture, the lens must be focused so that this place coin­cides with the plane on which the film sits.

Focal plane shutter - A camera shutter situated directly in front of the film, composed of an opaque curtain that contains a slit that moves directly across in front of the film, permitting light to strike the film.

Focal point - (1) The central or principal point of focus. (2) The optical center of a lens when it is focused on infinity.

Focus- (1) A point at which rays of light meet after being refracted or reflected. (2) Focal point of a lens. (3) The clear and sharply-defined condition of an image, as in “This image is in focus,” meaning it is sharp and well-defined. (4) Adjustment of the distance setting on a lens to obtain a sharply-defined image.

Focusing - Adjusting the distance between the lens and the film to form a sharp image of the subject on the film. The nearer the object you wish to focus on, the farther you have to move the lens from the film. On manual cameras you focus by moving the lens forward or backward by rotating a focusing control ring.

Focusing hood  - A cowl around focusing screens that shields the screen from light other than the light from the scene being photographed..

Focusing magnifier  - A simple magnifying lens that enlarges the image on a focusing screen.

Focusable light - With a focusable reflector, the light can be adjusted for different types of distribution and strength.

Focusable spotlight - The light from a focusable spotlight can be adjusted to produce a larger or smaller point of light, and sharper or less sharp light contours.

Fog or "Fogging" - Unwanted density in an image caused by accidental exposure to non-image forming light or X-rays, poor storage conditions or improper chemical processing.

Forced development - Another term for "Push-processing" - increasing development time of a film to "force" an increase in its effective speed.

Foreground - The area of a scene that is closer than the subject.

Format - The size or shape of a negative or print. The term usually refers to a particular film size, for example 35mm format, but in its most general sense can mean simply whether a picture is upright (vertical format) or longitudinal  (horizontal format). Cameras are usually categorized byte format of the film they use.

Frame - (1) The visible boundaries of a camera’s viewfinder. (2) The area of a single exposure on a film. (3) An element in a scene, like a branch or doorway, that frames the subject. (4) A decorative border surrounding a print.

Front lighting - A form of lighting in which the principal light source shines from the direction of the camera toward the subject.