In photography and videography there is what is known as the exposure triangle. ISO, Shutter speed and Aperture make up the three points and, by adjusting each one, you end up at the perfect exposure. As a baseline, I learned, in photography you shoot 1/ISO at f. 16 in sunny conditions, or what is known as the “Sunny 16” rule. Basically you start by setting your ISO, which was traditionally film so you’d have to use that ISO. So given that it’s a sunny day the ISO should be set quite low, say 100. Then setting the shutter speed to 1/100 (this is where you plug in the ISO number) and the f. stop to f. 16. You’ll get deep focus, a crisp image and clean from ISO noise. That’s great, like the old school auto mode- but with that comes problems when you want to flex your creativity. Say you want a blurrier background, or the subject is moving quickly and you need to freeze the action, or go in the opposite direction and blur the action? Well that’s the great thing about the triangle. When you pull at one point you can adjust one of the others, or a combination of the other two to maintain your exposure!
ISO, shutter speed and aperture all control exposure in their own way and come with unique benefits and draw backs you have to consider when you snap a shot.
ISO stands for International Standards Organization… which is pointless and no one cares about it. Moving on. ISO controls the sensitivity of your sensor, and while this sounds good on paper the draw back is that it WILL introduce noise into your footage at some point. Newer and more expensive sensors are good well beyond ISO 800. Some usable into ISO 6400 and beyond, others… not so much. If you’re shooting a lot of night shots the Sony A7s is a great body that has exceptional low light performance.
In photography the shutter speed can be as fast or as slow as you want it, with 1/125 of a second shutter speed as a baseline for shooting and getting rid of hand jitters. Image stabilization, vibration reduction, etc, can allow you to dip slower than that if your lens supports it. Shutter speed drops a curtain allowing light to hit the sensor for a predetermined amount of time giving you an exposure. The longer the shutter is open, the more light can hit the sensor, but also the chance that you shake the camera body offsetting the position the light hits the sensor causing blurring. In videography, the shutter speed should be twice the frames per second or FPS. So if you’re shooting at 24 FPS then the shutter speed should be 1/48, or 1/50 which is the closest. Increasing the shutter speed on your film will result in stuttery movement in your shots- it makes things seem unnatural or awkward to the eye because there is no motion blur. The human eye sees at around 24 fps and motion blur looks natural to the eye. This isn’t to say you should never shoot at a higher shutter speed. If you’re going to be doing a lot of green screen work a higher shutter speed is nice to pull cleaner mattes from.
Aperture is the opening in the lens that allows light through the lens into the camera body. The bigger the number the more the aperture closes down, and the less light can get through. Opening up the aperture the more light can get through, but this also decreases the area of focus and makes it easier to miss the key focus of the shot. This can be used to blur out the background and give your subject more focus, but it can also render a shot unusable if the focus is off.
In each direction you pull a point there is a pro and a con. Managing and balancing these pros and cons is one of the ingredients to an amazing photographer. There is no right or wrong way to shoot an image, all that matters is that you capture the shot YOU want to capture. If that means full auto shooting, that’s totally fine! If you want more control, use a shooting mode! If you can balance all three at once, good for you! That’s amazing! I personally use shutter or aperture priority mode, depending on what I’m doing, and if I have to I use manual, but that’s just me. Sometimes I’ll even use program mode if I’m just walking around snapping pics around town. The moral of the story is learn to use the triangle as a tool, but don’t get stuck thinking that’s the only way. Program modes and auto mode have their uses as well, don’t be afraid to use them! Good luck and happy snapping!