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Filmmaking terms starting with 4 include familiar video formats, film stocks, lighting equipment and sound settings. This section covers the differences between 4K rasters, chroma-sampling labels, four-foot frames, four-inch filters and other specifications that need more than a number alone.
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4:2:0 Chroma Subsampling
A video sampling arrangement that retains luma detail at a higher spatial resolution than chroma. In a common progressive implementation, each 2 × 2 block of luma samples has one Cb and one Cr sample. This reduces colour-data requirements but can make fine colour edges and chroma-key work less robust than higher-chroma formats. The notation does not specify bit depth, resolution or codec. Compare 4:2:2.
4:2:2 Chroma Subsampling
A video sampling arrangement with one pair of chroma samples for every two luma samples across a line. Chroma has half the horizontal sampling density of luma, while retaining its vertical sampling density. It generally preserves colour edges better than 4:2:0 under otherwise comparable conditions. “4:2:2” alone does not mean 10-bit, uncompressed or RAW; those are separate properties of the signal or recording.
4:3 Aspect Ratio
A frame four units wide for every three units high, equivalent to approximately 1.33:1. It is strongly associated with standard-definition television and also appears as a creative framing choice and in some camera modes. It should not be confused with the slightly wider Academy ratio of roughly 1.37:1. Image shape does not establish pixel dimensions or whether pixels are square.
4:4:4 Sampling
An arrangement in which the three image components have equal spatial sampling density: there is no chroma subsampling relative to luma in a Y′CbCr 4:4:4 signal. It is useful for demanding colour work and compositing, but is not automatically uncompressed or RAW. Bit depth and codec still matter. A fourth number, as in 4:4:4:4, commonly identifies an additional alpha component. Compare 4:2:2.
4-Perf 35mm
The conventional vertical 35mm film arrangement advancing four perforations for each frame. The exposed image area and final aspect ratio depend on the camera aperture and workflow; 4-perf does not automatically mean one particular widescreen ratio. At the same frame rate, it uses more stock per minute than 3-perf or 2-perf. A 400-foot roll lasts roughly 4 minutes 27 seconds at 24 fps.
4-Pin XLR
A four-contact XLR connector used on some production equipment for DC power, including cameras, monitors and lighting accessories. The connector shape alone does not guarantee a voltage, polarity or current rating. Check the exact equipment specification and approved cable before connecting a supply. It is a different connection from a three-pin microphone XLR and from five-pin DMX, even though all use the XLR connector family.
4Bank / Four-Bank
A Kino Flo fluorescent lighting system using four lamps in a fixture, traditionally available in nominal two-foot and four-foot versions with a separate ballast. The number describes the lamp bank, not a 4,000-watt electrical load. Lamp selection, accessories and the ballast’s switching arrangement affect the result. A four-foot 4Bank should not be confused with a 4′ × 4′ diffusion frame or treated as a generic name for every modern LED panel.
4K Resolution
An image-resolution family with roughly four thousand horizontal pixels. UHD commonly means 3840 × 2160, while the DCI cinema container is 4096 × 2160. Active cinema image dimensions can be smaller within that container, depending on the aspect ratio. Ask for the actual raster and delivery format rather than “4K” alone. Resolution also does not specify sensor size, bit depth, dynamic range or recording compression. See 2K.
4′ × 4′ Frame
A nominal four-foot-square grip frame used to hold diffusion, bounce or light-control material. The frame’s size does not identify its fabric: a silk, grid cloth, bounce and solid perform different jobs. Specify both size and material when calling for one. Support and securing requirements depend on the assembled setup and conditions, especially outdoors. These dimensions are feet, unlike a 4″ × 4″ camera filter.
4″ × 4″ Camera Filter
A square filter approximately four inches across each side, made for a compatible matte box or filter holder. It can contain ND, diffusion, colour conversion or another optical treatment; the size does not specify the effect. Check tray size, permitted thickness and lens coverage before use, particularly with wide lenses or stacked filters. It is not a four-foot lighting frame. See ND filter.
48 fps
A capture or playback rate of 48 frames per second. Shooting 48 fps and playing every frame at true 24 fps produces half-speed motion. Recording and playing at 48 fps instead gives real-time high-frame-rate motion. These are different uses, so state both the camera rate and intended playback rate. Match fractional rates appropriately when the base project is 23.976 fps.
48 kHz Sample Rate
An audio sampling rate of 48,000 samples per second per channel, widely used for production sound and video workflows. It describes temporal sampling of audio, not camera frame rate or bit depth. A 48 kHz recording may be 24-bit fixed-point, 32-bit float or another supported format. Agree the required sample rate with post before recording; changing a file’s playback interpretation can change its speed and pitch.
48V Phantom Power / P48
A DC power supply delivered through a compatible balanced microphone connection to power microphones or other devices that require it. On conventional XLR microphone inputs, it is applied to both audio signal conductors relative to the shield. It is different from the low-voltage plug-in power used by many small camera microphones. Follow the microphone’s requirements, especially for ribbon mics, unusual wiring or adaptors; not every microphone needs phantom power.
400-Foot Roll / 400-Foot Load
A film quantity rather than a fixed recording duration. For 35mm stock at 24 fps, 400 feet gives approximately 4 minutes 27 seconds in 4-perf, 5 minutes 56 seconds in 3-perf, or 8 minutes 53 seconds in 2-perf. Usable shooting time is lower after allowing for loading, run-up and other stock requirements. The gauge, perforation format and speed must always accompany a footage estimate.
Precise units and complete signal specifications prevent a lot of unnecessary confusion on set. State the size, format or function along with the number when ordering equipment or handing material to post. Continue with terms starting with 5, or explore the main dictionary hub.
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