What is ISO in DSLR?

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Updated November 14, 2022

If you are new to digital photography, you may wonder what is ISO in DSLR. Many of the best digital cameras, after all, are DSLR models, and these cameras can be adjusted to suit various ISO parameters. So what exactly does ISO mean, how does it impact the best DSLR cameras, and what tips should you keep in mind? Keep reading to find out.


  • ISO stands for International Organization for Standardization, though it actually has very little to do with the correlating regulatory agency.
  • With DSLR digital cameras, ISO refers to how sensitive the gadget is to light. This impacts image quality, digital sensors, depth of field, and more.
  • Generally speaking, a low ISO creates darker images, while a high ISO creates brighter ones.

What is ISO on a DSLR Camera?

When learning how to set up a DSLR camera, it is important to understand ISO. The term stands for International Organization for Standardization, which is a regulatory agency that handles universal measurements if you are conducting a camera comparison of a Sony Alpha 6000 vs a Nikon D5300. Funnily enough, though the term ISO was adopted via the agency, it actually has nothing to do with it, so contacting this agency will not help you, for instance, learn how to reset a DSLR camera.

Insider Tip

ISO is not the only metric of a camera that refers to how much light is allowed to meet the lens and sensor, as shutter speed also impacts here.

When it comes to cameras, ISO refers to how sensitive the gadget is to light, even if you are comparing a Blackmagic Ursa V1 vs V2. A camera’s sensitivity to light directly impacts your photos, and you want a model with plenty of range here if you are learning what to check when buying a used DSLR.

ISO Settings Tips

ISO is a relatively simple concept with some major implications for your photos. Here are some tips worth considering to help wrap your head around the idea so you can make adjustments to better your photography.

Learn the Lingo and Uses

ISO is measured in simple numbers, like 100, 200, or 400, though some cameras represent this as a fraction (for example, 1/100 or 1/400.) Changing this number changes your camera’s sensitivity to light, which brightens or darkens your image. The basic gist? The lower the ISO, the darker your image will be; the higher the ISO, the brighter your image will be. This isn’t the whole story but it is enough for now.


The best way to get a handle on ISO settings is to “just do it.” Experiment with different ISO settings in different environments. Try a low ISO at night to see what happens or a high ISO at noon while outside. Then try the exact opposite in both scenarios. Finally, make some middle-ground adjustments.

STAT: A low ISO is technically going to give you the best image quality possible. (source)

Go Automatic

You don’t have to learn about ISO at all, as the camera’s automatic setting will handle all of the adjustments for you. This is worth considering, especially if you are a beginner.


How do you change ISO?

Changing the ISO setting to allow for a correct exposure or proper exposure depends on the camera itself, as the process differs.

What is base ISO?

Base ISO is the lowest ISO setting on your camera and does not impact the depth of field. It does, however, impact the ISO speed, the image sensor, exposure time, and more.

What's the difference between ISO and shutter speed?

Think of ISO as a motion slider allowing light in and shutter speed how long that light is allowed in. A faster shutter speed makes the shutter close quickly, allowing for minimal light. This does not impact the depth of field but is important when it comes to brightness.
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