When lighting things such as interviews, documentaries and news sets you use something called the three point lighting system. The three point lighting system consists of three types of lights: main source light/s, filler lights and backlights.
Main source light
The main source light or key light is the strongest light. The purpose of this light is to give out as much light as possible onto the set. It is usually placed to the side of the camera so that the side you are wanting to see most of the subject is well lit.
Filler lights
Filler lights fill the shadows created by the main source light. These lights are usually spotlights which gives make them the ability to be much softer and less brighter than the main source light. On the light itself to change how soft it is, you can move a slider which alters this. However with any light, you change the intensity of them by moving them further or closer away from the subject.
Backlights
Backlights are used at the back of a subject, either low down or high up. The purpose of these lights are to highlight the subjects outline you can usually tell when the back light is correct as you can see the hair outlined. One problem with back lighting is the intensity and position can give halos behind a subject so it is important to position them correctly.
When lighting factual pieces, it is important to get as much light as possible on set as well as making it consistent. Things like news sets often have subjects walking around them so making the light consistent on set is important. The light can be measured on a device called a light meter, this also helps with exposing your shot properly with your camera using the correct aperture.
In practice, as group we lit a mock interview using the three point lighting system. We found that when used correctly with knowing the correct position to place the lights, the shots were well lit and using a light meter helped expose the shot properly.
(https://www.mediacollege.com/lighting/three-point/)
This image demonstrates the three point lighting system. (I did not produce this image)
(https://goo.gl/images/eSYB37)
-Joshua Poole- 