The Exposure Triangle
Illuminati! Oh wait, wrong triangle. In this episode, we will be thinking like a camera operator. Here at Atlanta Idea Studio, we can’t stress the importance of proper exposure enough. Unless you are trying to veer away for aesthetic reasons, most videos and films follow the same exposure techniques.
The exposure triangle refers to the three controls on your camera that adjust the amount of light that hits your camera’s sensor or film. Those three controls are aperture, shutter speed and ISO. Basically, these three controls determine if your shots are blown out or crushed. Typically, that’s a no-no, so we expose to where everything is balanced out in a way that is pleasing to the eye. This allows us to actually see what is going on in our video. This is called correct exposure. Each element in this triangle works together interchangeably.
Let’s start with ISO. ISO is the sensitivity of the sensor to light and it may seem like the simple fix to brightening up some dark scenes; but the truth of it all is that ISO really adjusts how much grain (or noise) you are allowing into your video. Grain is usually undesirable, and most people do not want it in their films. What I’ve found that works best is finding what’s native for your camera, usually around 800 ISO and filming with that on indoor scenes. But when you are filming outside, you want your ISO very low. This is dependent on the camera. Personally, I would put it at around 400 ISO. This will take out that grain. Once you set your ISO, you usually don’t have to adjust it because you don’t want to bring it up.
Next, we have our aperture. Aperture plays a large role in depth of field. You will find that your aperture is determined by your focal length, which is commonly referred to as the F/stop. F/ stop is on your lens. The lower the number, the wider the aperture and vice versa. A wider aperture lets in more light through the lens and this allows for a shallow depth of field. The higher your raise your F/stop, the deeper the depth of field becomes. I usually only use high F/stops whenever I’m filming sunsets, otherwise, I like to keep my F/stop between a 2.8 to an 8. (Fun fact: Polarizers can help you get a shallow depth of field without having to jack your F/stop really high).
Lastly, we have our shutter speed! This has to be my favorite part of getting perfect exposure. To sum it all up, shutter speed is how fast the iris opens and closes to let in light to the sensor. It is seen as a fraction and in video, it is usually twice your frame rate, aka frames per second (FPS). You can do so much with your shutter. You can slow it down (1/4) and get long explosure shots or you can speed it up (1/120) and get awesome action scenes. Basically, it controls motion blur. A slow shutter speed makes more blur, while a fast shutter speed is more crisp with less motion blur.
Once you understand how these three variables for exposure work in coordination with each other, your creativity is endless. You can do so much with this and tweak it until you find “your look”. This is why the exposure triangle is crucial to understanding when it comes to video production and filmmaking, and this is just the beginning.