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Nano. A one
millionth 10-9 .
A filter that attenuates all colours of light in the visible spectrum,
ND Spot. A
graduated "spot" filter in a lens that restricts the amount of light
through the lens at small apertures.
Nit. A measurement
of luminance = 1 candela/ m2.
Noise. Any unwanted
signal produced by all electrical circuits working above the absolute
zero. Noise cannot be eliminated
but only minimized.
The process of scanning whereby every line in the picture is scanned
the vertical sweep.
NTSC. National Television
Systems Committee. American committee that set the standards
for colour television as used today
in the US, Canada, Japan and parts of
NTSC television uses a 3.57945
MHz sub-carrier whose phase varies with the
hue of the televised colour and
whose amplitude varies
with the instantaneous saturation of
the colour. NTSC employs
525 lines per frame and 59.94
fields per second (usually taken as
60 fields per second).
A number that defines the light gathering ability of a specific optical
aperture is equal to the sine of the maximum acceptance angle.