The user selects {TAIL ~ maximum gain} to cause {HEAD ~ a scene} to go dark at a certain low light level rather than gaining up to a noisy image 
The user selects { TAIL ~ maximum gain } to cause { HEAD ~ a scene } to go dark at a certain low light level rather than gaining up to a noisy image
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH