Last Updated 2 days ago
Filmmaking terms starting with 0 often describe reference levels or filter strengths. This section explains what zero means on different audio and video scales, alongside the 0.3, 0.6 and 0.9 ND filters you will encounter in a camera package.
Browse by number:
Browse A–Z:
0.3 ND
A neutral-density filter with an optical density of 0.3, giving approximately one stop of light reduction. It transmits about half the incoming light. This lets you open the aperture by one stop while keeping the same exposure, assuming the other settings stay fixed. The decimal describes density, rather than a filter’s physical size. See ND filters.
0.6 ND
A neutral-density filter giving approximately two stops of light reduction, transmitting about one quarter of the incoming light. It is stronger than 0.3 ND but weaker than 0.9 ND. Optical-density values add when compatible filters are stacked: two 0.3 filters produce a nominal density of 0.6, although stacking can introduce reflections or colour shifts.
0.9 ND
A neutral-density filter giving approximately three stops of light reduction. It transmits about one eighth of the incoming light. Optical density and filter-factor labels use different scales: 0.9 ND is commonly described as ND8, while ND0.9 identifies the density directly. Check the manufacturer’s labelling rather than assuming every number printed on an ND filter means stops.
0 dB
A decibel value indicating no difference from the stated reference. For example, a gain setting of 0 dB means unity gain at that stage: the signal is neither amplified nor attenuated relative to the reference setting. It does not mean silence. Always identify the scale; 0 dBFS, 0 dBu and 0 dBV describe different things.
0 dBFS
Zero decibels relative to digital full scale. In conventional fixed-point digital audio, this is the upper sample-level limit; recording beyond that limit clips the signal. It is not a sensible default dialogue recording target. 32-bit floating-point files can represent values above this reference, but microphones, analogue inputs and playback outputs still have physical overload limits. Sample peaks and reconstructed true peaks also differ.
0 VU
The nominal reference mark on a volume-unit meter. A VU meter responds relatively slowly and indicates average programme level rather than catching every brief peak. Zero VU is not the point where a recorder necessarily clips. Its relationship to dBu or dBFS depends on the equipment and alignment settings, so confirm the calibration when matching a mixer to a recorder.
0 dBu
An audio voltage reference equal to approximately 0.775 volts RMS. The scale describes an electrical signal level, not digital headroom or the loudness reaching your ears. Professional analogue equipment often uses a nominal level above this reference, such as +4 dBu. A recorder’s 0 dBFS point can correspond to a different analogue input level, depending on its calibration and gain settings.
0 dBV
An audio voltage reference equal to 1 volt RMS. It uses a different reference from dBu, so identical numbers on the two scales do not represent identical voltages. The distinction matters when comparing microphone sensitivity, line outputs or recorder inputs. Neither dBV nor dBu tells you an equipment connection’s purpose, connector wiring or maximum safe input level on its own.
0 IRE
A point on a video waveform scale, commonly used as the nominal black reference in SDR component-video monitoring. It is not a universal instruction to push every dark object to the bottom of the waveform. Signal range, transfer function and monitoring transforms affect where camera footage sits. Historical analogue NTSC setup used 7.5 IRE for black in some systems, which should not be added indiscriminately to digital footage.
When a specification says zero, identify the scale before changing a setting. An audio reference, a video level and a filter density belong to different systems. Continue with terms starting with 1, or use the filmmaking dictionary to follow the wider subject.
Browse by number:
Browse A–Z: