Sound is to microphone as light is to lens. Pretty basic common sense in filming, so why is it necessary to teach this stuff anyway?
Firstly, just because it is basic common sense, let’s not assume that everybody knows it. One of the first things I was taught when doing photography was that the lens of the camera was like your iris. Your iris (equivalent to the ISO on the camera) will expand to let in as much light as is needed in order for you to see. And while this is so your iris cannot create light that does not already exist. Similarly, your camera’s exposure can be set to the lowest or highest point in order to determine how much light is let into the lens. This is why lighting is so important in photography and videography.
Secondly, How much lighting and the type of lighting you have on a shoot can make a world of a difference with how your footage comes out. Aside from the obvious – low lighting equals dark footage – the lighting also affects the mood of the footage.
For example, a low light can sometimes mean suspense or horror and soft light can mean romance. Lighting helps set the mood of each scene and therefore is of vital importance when filming.
Finally, a great way to add light to your set without a bunch of expensive LED lights is by using props for lighting. So, in a romantic scene instead of adding light, simply use a bedside table lamp with just enough light to set the mood and light the actors. Or an even better way to save on both electricity and money is to film during daylight. The sun is still free…for now.