If you have gaffers around in Pre-Production, they should order the production’s lights from the vendors. If the key grip is the cinematographer’s left hand man, the gaffer is the guy on the right. The gaffer turns the DP’s conceptual idea for the image into a technical reality with their knowledge of things like scrims, diffusions and their characteristics, color temperatures, the gels required to achieve those color temperatures and oh – you know, lights.
The Electric Department
The electric crew is responsible for turning the lights on and off, which is a much bigger job than it sounds like, because sure – anyone can set up a lamp with a nice shade in the shot, but does anyone know how to mimic that light and make it usable enough to play on camera? Oh – now you're listening. On top of that actually really important responsibility, they also keep the set from burning down, at least from any accidental cause...Oh – now you're really listening.
Gaffer | Chief Lighting Technician
So while the gaffer is the right hand man of the cinematographer, the best boy is the gaffer’s right hand man…one big happy conga-line-hand-holding-light-train. When the gaffer figures out the technical needs for the shot, the best boy actually figures out a way to set it all up so that it works – the logistics. This video explains it quite succinctly:
Electricians | Lighting Technicians
The electricians and lighting technicians are the hands of the gaffer and best boy. Now we’re making it seem like everyone’s just holding hands on set. But realistically, it might just be two hands, and chances are they belong to you because you can’t afford all these people anyway. Electricians and lighting technicians perform all the actual physical handling of the lights, as well as remembering to plug them in to the outlet. They also man the controls of the auxiliary equipment, consoles and generators to make sure that whole burning down the set thing doesn’t happen. However, if something does go wrong and you do have these guys on set, you will definitely get a call from their union.