What is ISO on my camera?
ISO is the measure of a camera sensor’s sensitivity to light.
The easiest way to explain it is, low ISO is less sensitive to light, and high ISO is more sensitive to light.
So change your ISO on your camera according to how much light is available.
ISO settings are represented by numbers such as 100, 200, 400, 800, 1600, 3200 and so forth.
The lower the ISO number (i.e. 100 or 200), the less sensitive a camera sensor is to light.
As a general rule, you’d want to use a low ISO on bright sunny days where there’s plenty of light. If the rest of your settings are correct, a picture taken at a low ISO number will give you more vibrant colors to your image.
Low ISO number means your digital camera sensor will have a higher tolerance to bright light, as if your camera sensor is wearing sunglasses on a sunny day.
Higher ISO number means the camera sensor is more sensitive to light. At a high ISO, you’d be able to to take photos even in low light situations.
Traditionally, images taken at high ISO will end up with some noise a.k.a. grain(little specks). You’ll also lose some color depth, causing the colors to look less vibrant.
However, in recent years, companies like Canon and Nikon have produced some high-end cameras that produce high quality images without much noise, even at high ISO.
The good news is, you don’t necessarily need to spend money on a high-end camera that performs well in high ISO. Investing in lenses with wide apertures like 2.8, 2.0 or 1.8 enables you to keep your ISO lower because wide apertures bring more light in to the camera.
For example, if you’re taking pictures at your daughter’s dance recital in a dark concert hall, and all you have is a kit lens that gives you an aperture at f/5.6 when zoomed in at 55mm. Let say, your settings are aperture f/5.6, shutter speed 1/60 at ISO 1600. You can go to ISO 800 and shutter speed 1/30 but because that’s slower shutter speed your photos might turn out all blurry, due to movement and camera shake.
But, if you had a lens like the 50mm 1.8 lens that has a wide aperture that brings in more light, you’d have the freedom to change your setting to a wide aperture like f/2.0, with shutter speed 1/125 and ISO 400, or something like f/1.8, 1/160, ISO 400. You wouldn’t have to necessarily shoot at a high ISO like, ISO 1600 and risk getting images full of grain and noise. Or you wouldn’t have to shoot at a slow shutter speed just to bring in more light. A slow shutter speed like 1/30 will likely result in blurry images. Make sense?
Here’s another scenario. You might be in a situation where you have to increase your ISO even when there’s plenty of light, because you want or need a faster shutter speed.
For example, you’re taking pictures at your kid’s baseball game, and want to freeze the action. A faster shutter speed freezes action. So, let’s say, you’re getting proper exposure at ISO 100, shutter speed 1/160 and you like your aperture to be at f/2.8. But you’re getting some motion blur as the players are moving around because at shutter speed 1/160, your shutter speed isn’t fast enough to freeze some of the fast action. In this case, you need to increase your shutter speed to something like 1/640 or above. How do you change the setting while keeping the same exposure? What do you do about the ISO? Assuming you want to stay at aperture at f/2.8, if you keep your ISO at 100, your image will be underexposed(too dark).
You’d have to increase your ISO to 400 to get the same exposure you had. So from ISO 100, f/2.8, 1/160, you can change your setting to ISO 400, f/2.8, 1/640. You’ll get the same correct exposure as before but now you can freeze the action.
Try and see what different ISO settings do to your images, see how shutter speed and aperture change.
If you’d like further technical understanding of ISO, Dylan Bennett does a superb job explaining it in the video below.