A) The magnitude of the output when reproducing a tape recorded with a signal of given magnitude and frequency. The sensitivity of an audio or instrumentation tape is normally expressed in dB relative to the sensitivity of a reference tape measured under the same recording conditions.

b) The amount of signal a camera can emit from a particular sensor illumination at a particular SNR, sometimes expressed as a certain scene illumination (in lux or foot-candles) at an assumed reflection and signal strength, at a particular lens transmission aperture, at a particular SNR.

The sensitivity of a camera can be truly increased by improving its image sensor, increasing its transmission aperture, or slowing its frame rate; it can be seemingly increased by allowing the SNR to be reduced. All other things being equal, at this time the sensitivity of an HDEP camera is less than the sensitivity of an NTSC camera. The sensitivity of first-generation HDTV 1125 scanning-line cameras is two to three stops less sensitive than that of a 525-line camera (needing four to eight times as much light).

HARP tubes and new CCD advances may offer a solution to this problem.