Let’s get a little technical! Today we’ll discuss ISO, how it affects your photos, and what settings you might use.
ISO is how much light sensitivity a photographic film or digital sensor has. The higher the ISO, the more sensitive the sensor is to light and the more grain you could potentially have. Since we are almost all shooting on digital cameras, the ISO can be changed from shot to shot giving us more control over the lighting in our images. Back in the film days, the film dictated the ISO, and it had to stay at whatever the film dictated, leading to less flexibility in adjusting the light in a photo.
Grain is the noise you may see in an image shot at a higher ISO. If you are shooting in a dark restaurant without flash, you will definitely have some grain because your ISO will need to go up. When shooting outdoors it is easy to keep your ISO low and keep grain out.
When you are photographing a very well lit situation, like outside on a bright day, you would probably set your ISO somewhere around 100 and have zero grain. If you are inside a well lit space on a bright day, it might be somewhere around 400 and have little to no grain. And inside on a dark day, you’ll probably be somewhere around 1600 ISO, with a fair bit of grain. You can see in the cart below how ISO affects grain.
There are other settings you can use to avoid grain in conjunction with ISO, which we will talk about later on, so stay tuned!