How Professionals Measure Camera Sensitivity Professional videographers take camera specifications very seriously, and so do manufacturers of professional video products. For this reason, professional camera specs are very precise. When professionals compare cameras, they make sure that the lenses used are at the same f-stop and focal length. They will also tell if the gain was boosted in order to make the measurement. The number of TV lines of horizontal resolution will also be mentioned.
Professionals define the brightness of a picture in terms of numbers and voltages.
IRE stands for Institute of Radio Engineers and represents a measure of video signal strength observable on a special oscilloscope that graphs the electronic video wave. How Consumer Cameras Used to be Rated Unfettered by standards, manufacturers would do whatever was necessary to make their cameras appear to be sensitive in low light. They would lower the shutter rate, even though it smeared the picture, and would pair the light sensitive CCD elements together, even though it reduced camera resolution. Then they would boast that they had a picture even though it was dim and grainy. For this reason we have seen many camcorders sport a 1 lux rating here in the U.S. while the same camcorder lists a 7 lux rating in Japan where standards of lux measurement have been in place for some time.