Photography terms starting with F

F-number Exposure & Metering Dimensionless ratio The ratio of a lens's focal length to the diameter of its entrance pupil, written f/2.8, f/8 and so on, and the standard way of stating aperture. N = f / D

Face Detection Focus & Depth of Field A system that identifies human faces in the frame and prioritises them for focus and often for exposure.

False Colour Sensors & Digital Capture Coloured artefacts appearing on fine detail, caused by the colour filter array sampling different colours at different positions.

Farm Security Administration Genres, Movements & Theory count A United States government programme of the 1930s and 40s that commissioned photographers to document rural poverty during the Depression.

Fashion Photography Genres, Movements & Theory Photography made to present clothing and to construct a mood or identity around it.

Feathering Lighting & Flash Aiming a light so the subject is lit by the softer edge of its beam rather than its centre.

Fibre-based Paper Film, Darkroom & Historic Processes g/m² Photographic paper whose emulsion is coated directly onto a paper base with no plastic layer.

Field Camera Cameras, Formats & Systems A folding large-format camera built light enough to carry, trading some movement range for portability.

Field Curvature Optics, Lenses & Filters A defect in which a lens focuses a flat subject onto a curved surface rather than the flat plane of the sensor.

Figure-Ground Relationship Composition & Visual Design The perceptual separation of a subject from its background, which determines whether it reads clearly.

File Naming Convention Files, Metadata & Workflow A consistent rule for naming image files so they sort predictably and stay unique.

File Size Files, Metadata & Workflow MB The storage a file occupies, determined by pixel count, bit depth, channel count and compression. Bytes ≈ px × channels × bits / 8

Fill Light Lighting & Flash f-stops (EV) A secondary, weaker light or reflector used to raise the shadows the key light casts, controlling contrast. Ratio = key / fill

Filling the Frame Composition & Visual Design Composing so the subject occupies most or all of the picture area, leaving little surrounding context.

Film Film, Darkroom & Historic Processes mm / format A flexible transparent base coated with a light-sensitive emulsion, which records an image chemically rather than electronically.

Film Base Film, Darkroom & Historic Processes µm The transparent support that carries the emulsion, historically nitrate or acetate and now usually polyester.

Film Grain Film, Darkroom & Historic Processes RMS granularity The visible texture produced by clumps of developed silver, which becomes more apparent with faster films and greater enlargement.

Film Simulation Post-Processing & Retouching A colour and tone rendering designed to imitate the response of a specific photographic film.

Film Speed Film, Darkroom & Historic Processes ISO A film's sensitivity to light, rated on the ISO scale and formerly as ASA or DIN. ISO arithmetic = 2^((DIN−1)/10)

Filter Factor Exposure & Metering stops (EV) The exposure increase, in stops or as a multiplier, needed to compensate for the light a filter absorbs. Stops = log₂(factor)

Fine Art Photography Genres, Movements & Theory Photography made primarily as an expressive work rather than to document, illustrate or sell a product.

Fisheye Lens Optics, Lenses & Filters mm An ultra-wide lens that deliberately abandons rectilinear projection, bending straight lines to squeeze 180° or more into the frame. r = f × θ (equidistant)

Fixed Pattern Noise Sensors & Digital Capture Noise that appears in the same places on every frame, caused by small manufacturing differences between photosites.

Fixer Film, Darkroom & Historic Processes minutes A solution that dissolves the undeveloped silver halide, making the image permanent and no longer light-sensitive.

Terms starting with F