ISO stands for the International Organization for Standardization — an organization that sets international standards for all different kinds of measurements. But, when in reference to your camera, the ISO is your camera’s sensitivity to light. ISO is displayed in a number like this: 100, 200, or 400. Essentially, when you adjust your ISO, you’re changing your camera’s sensitivity to light (i.e., you brighten or darken your image).
The ISO is how you can adjust the exposure on your camera. It’s one of the three main pillars of exposure — along with shutter speed and aperture. Changing the ISO will brighten or darken your image. When it comes to measuring the ISO, the lower the ISO, the darker your image will be; the higher the ISO, the brighter your image will be.
Changing your ISO for photography will make your image brighter or make your image darker. Typically, the lower the ISO, the better. That’s because the lower the ISO, the less noise and grain you’ll have in your shots.
ISO for video is basically the same as it is for photos. When you adjust the ISO for your videos, they’ll be brighter or darker. And just like with photos, the lower the ISO, the better, because your image quality will be crisp and clear. Higher ISOs tend to look noisy or grainy.
A low ISO is technically going to give you the best image quality possible. If you use an ISO of 100, and your image is properly exposed, this is the best scenario to be in. This means, you’ll be getting pretty much the best quality out of your camera. Now, when it comes to higher ISOs, of even 3200 or higher on some cameras, you’ll start to experience noise and grain. The higher the ISO, the more grain and noise you introduce to your image. That in mind, try to keep your ISO low if possible, and only raise it when you need to! One thing to note when it comes to ISO is that all of this is also relative to your camera. Some cameras are great in high ISOs while others have very noticeable grain. It’s best to test with your own camera to see its capabilities.
Typically the best ISO setting for video is a low ISO. An ISO between 100–200 is going to give you the best result. You’ll also want to consider your camera’s native ISOs. What are native ISOs? Well , they’re the ISOs your camera performs best at. For example, when it comes to Canon cameras, the native ISOs are 160, 320, 640, 1250, 3200, etc. It’s usually structured the same way for other cameras, too. You’ll often see that native ISOs are doubled as they increase. If you stick to native ISOs while brightening or darkening your image, you’ll notice less grain, and get — overall — a better quality image.
So, if you’re opening up your camera to shoot a video, choose a low ISO like 160 if you’re on a Canon. And then brighten up your image if you need to with shutter speed and aperture. For setting exposure, you should follow this order: ISO, then aperture, and finally shutter speed to get the best results.
If you’re shooting in low light, a high ISO is best (e.g., 3200, 6400, or anything higher). A higher setting will help you achieve a well-balanced shot in low light. If you can, you should still try and stick to native ISOs. And even if you get a little bit of noise and grain, you can still push your camera if you need; it’s all about getting the shot. So, if that means you have to boost your ISO to get a proper exposure, do it!
High ISOs typically have a lot of noise and grain associated with them because it makes the camera sensor absorb light faster. That means, the higher the ISO, the harder the image sensor is working to produce a good image, which sometimes produces more digital noise or grain.
ISO and shutter speed are both products of image exposure or brightness. I like to think of ISO as an exposure slider; its main purpose is to brighten or darken your image. Shutter speed is more related to motion blur in video and capturing fast-moving objects in photography.