The very first thing you’re likely to hear while working with a camera is something called “the three pillars”. This refers to the aperture, the shutter speed and the ISO. And they will be the key to making a high quality, well illuminated scene. This is something you want to make sure to understand completely as it will save you a lot of time when setting up. Here’s what you need to know:
How Much Light Goes into the Lens
Aperture: this refers to the diameter of the opening of the lens that allows light into the camera. In plain English, this is what tells you how much or how little light comes through the lens. Aperture is measured in f-stops, the most common are 1.4, 1.8, 2.0, 2.8, 4.0, and 5.6. While some photographers and videographer know those numbers by heart, it’s not really necessary.
Just remember that the smaller the number, the more light it lets in; conversely, the bigger the number, the less illumination it gives off. So, working with an f 1.4 would mean more light is getting in than when working with a 5.6. This is also what makes a lens affordable or prohibitively expensive. Naturally, the lenses with the lower numbers will cost you more.
Sensors and the Entrance of Light
Shutter Speed: this is the amount of time the camera’s shutter will let the light in. That is a long shutter speed will mean the camera or the camera’s sensor is exposed to light for a long period, and a short shutter speed means exactly the opposite. Shutter speed is measured in fractions of a second.
On still photography, you’ll see this represented as, well, an actual fraction, such as 1/200, or 1/60, meaning the shutter is open for a 1/200 of a second or 1/60 of a second accordingly. Longer shutter speeds are usually used to capture time lapses in a single picture in photography.
Footage’s Sensitivity to Light
ISO: usually ISO is referred to as the relationship between exposure (we’ll cover this in a second) and brightness in an image after it has been taken. It doesn’t really affect how much light goes through the lens or through the sensor but rather, how sensitive an image will be to brightness. ISOs go from 100, 200, 300, 400 and 800 though must cameras can kick up to the 3000. Be careful though as the higher you go, the more chance you have of ending up with a grainy or noisy image.
Another word, deeply related to the three above, is exposure, referring to the amount of light reaching the sensor. That is how well-lit or how dark an image ends up being. Typically, after setting the right ISO, videographers and photographers will work on their aperture and shutter speeds to make sure an image is well exposed, which brings us to a whole other issue. An image is well exposed when it has just the right amount of true blacks and true whites. It’s overexposed when it’s too white (because the sensor received way too much light) with dark greyish blacks, and it’s underexposed when it’s too dark (because it didn’t receive enough light). While you should try to achieve a balance, in reality, it depends on your tastes and the moods you’re trying to achieve with your footage. Wes Anderson tends to have really bright, almost overexposed images, yet no one will say his aesthetics are wrong. Likewise, Park Chan-Wook goes for a more dark, underexposed look, and he’s still considered a great filmmaker.
A final term that you need to know is depth of field. It refers to the distance the image remains in focus. Think of those portraits in which the subject is sharp and easy to see while the immediate background looks blurred and fuzzy, that kind of portraits are taken by photographers increasing the aperture to decrease the depth of field and create that blurred background effect. It’s a commonly used technique to draw attention to the subject while eliminating background distractions.