Nanometer:
is a unit of length. 1 nm = one billionth of a meter or 10 -9 m.

Neutral density filter:
is a type of filter used with lenses which reduces light of all wavelengths equally.

Noise:
is an unwanted signal generated by every electronic component. The noise in a video signal causes a grainy or snowy effect on the image.

NTSC National Television System Committee:
is a colour television system and the standard used in the USA and Japan. NTSC has 525 horizontal scanning lines and 60 fields per sec.