First, let’s break down the acronym. ISO is short for International Standards Organization – the main governing body that standardizes sensitivity ratings for camera sensors. It’s a a term that was carried over from film. When you change your ISO setting, you’re adjusting your camera’s sensitivity to light. ISO settings can be anywhere from 24 to 6,400 (or higher), and these numbers have a direct relationship with the device’s sensitivity, so a lower setting makes it less sensitive and a high setting makes it more so. Along with shutter speed and aperture, ISO is one of the three factors that determine your picture’s exposure. Finding the right balance between these three settings is key to getting the perfect shot.
Finding the right ISO setting
First of all, you should know that a higher ISO typically translates to a noisy or “grainy” image, so as a general rule you want to use the lowest setting possible for your photos. Check out the picture below to see the difference it can make.
A lower ISO will usually produce more color-accurate, aesthetically pleasing images, but there are situations where a higher ISO is desirable. The proper ISO setting really depends on the level of lighting you’re shooting in and the visual effect you’re going for, so rather than relying on one over-arching rule, consult this list of tips:
If your subject is moving and you’re trying freeze the motion for a still, you’ll likely need a higher ISO setting to compensate for the high shutter speed and ensure your image gets enough light
If you’re going for more of a vintage aesthetic and want to add a little bit of grain to your photos, don’t be afraid to bump up the ISO a few notches
If you’re using a tripod to stabilize your camera you can usually get away with a slower shutter speed, which in turn allows you to use a lower ISO
If you’re shooting an image that doesn’t require a large depth-of-field, you can increase the camera’s aperture (thus allowing more light into the lens) and use a lower ISO
If you’re shooting with artificial light (i.e., using a flash) you can typically get away with a lower ISO setting
You’ll probably need to experiment a bit until you hit the sweet spot, but while you tinker with settings, keep the following in mind:
Never trust your camera’s display. Don’t assume that your picture will turn out just because the tiny 2-inch preview looks adequate. Your shots almost always look different on your computer, and you probably won’t be able to spot noise on your camera’s small, low-resolution display. For this reason, we highly recommend that you zoom in a bit to check your images for grain. There’s nothing worse than taking a bunch of seemingly great shots only to discover they’re noisy and speckled when you upload them to your PC.