Electronic shutters
The electronic shutter varies the length of the pulse that reads out the charge on the CCD. With the electronic shutter switched out, the PAL ‘picture’ exposure time is 1/50th second. The electronic shutter reduces this exposure time by switched steps, improving reproduction of motion but reducing sensitivity.
One complete frame of the standard PAL television signal is made up of two interlaced fields with a repetition rate of 50 fields per second (25 complete frames per second). The CCD scans the image 50 times a second which is the ‘normal’ shutter speed of a PAL video camera). CCDs can be adjusted to reduce the time taken to collect light from a field (see figure below), and reducing the length of the readout pulse is equivalent ...
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