DSLR Photography 101: What is ISO?

Megan O'Neill


DSLR cameras are growing in popularity. If you’ve recently jumped on the DSLR bandwagon you can understand why – the photos and videos they take are amazing. But with so many settings, taking the dive from automatic to manual can be daunting. That’s why we’re launching a DSLR Photography 101 series.

Over the coming weeks, we’ll explore the manual settings on your DSLR camera – ISO, shutter speed, and aperture – as well as tips on shot composition, and more. We’ll start with ISO.

You’ve probably seen the ISO button on your camera, but may have wondered what exactly it is. ISO determines how sensitive the sensor in your camera is to light.

Setting a higher ISO will let you capture images in low-light environments without the use of a flash. However, it’s important to note that as you increase the ISO your image will have added noise or grain. You can see what we mean in the image below. As you can see, the photograph taken at ISO 5000 is much grainier than the photograph taken at ISO 100.

DSLR Photography 101: What is ISO?

Because of this noise, our Consumer Customer Owner Beth Forester, who also happens to be a professional photographer, says, “I’m always looking for the lowest ISO I can use in order to get the cleanest file possible.”

Depending upon the type of camera you have, Beth says that noise will start to appear around 400-640 ISO. However, if you don’t have a flash or are looking for a flashless look in low light, grain is sometimes unavoidable.

Here are our recommendations for how you should set your ISO, depending on where you are shooting and what type of light you are in:

  • Full sun – 100 ISO
  • Open shade (i.e. under a tree, in the shade of a building) – 400 ISO
  • Overcast – 400-640 ISO
  • Late evening, before sunset – 640-800 ISO
  • Indoors with average light through windows – 800-1000 ISO
  • Dark indoor scenes (i.e. a school play, a concert) – 1600+ ISO

The good thing about a DSLR camera is that you can preview photos as soon as you take them, so if your photo looks too light, too dark, or too grainy you can always adjust the ISO until you find a setting that works for you. After you take your photo, zoom in on the display to see if the grain is acceptable.

Stay tuned for the upcoming posts in our series, where we’ll explore aperture and shutter speed and how, paired with ISO, you can use them to shoot amazing photos.

Do you use a DSLR camera? How do you like it? We’d love to hear from you in the comments.

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