What Is ISO In Photography? – The Complete Guide For Beginners

As you begin to learn how your camera settings work, you still may be unclear about what ISO does for your photography. ISO is the third key pillar of exposure in photography and plays a more significant roll in the photos you take than you might think!

In this article, you’ll discover the importance of ISO in photography, how to best use it, and some tips to avoid going overboard with your ISO settings. If you’re new here and haven’t seen the previous posts in this beginner photography settings series, make sure to check out the best camera settings for beginner photographers, understanding shutter speed, and why aperture matters in your photography.

One last thing before I jump into everything you need to know about ISO in photography, make sure to grab your Manual Mode Cheat Sheet to use as your handy reference guide to perfect camera settings where ever you go! You can click here to get access to the free Manual Mode Cheat Sheet. It’s amazing to help memorize ISO settings so you won’t want to miss this one!


What Is ISO In Photography


ISO is one of the three primary camera settings that affect the exposure (aka brightness) of your photo. When you adjust your ISO setting, you’re actually changing how sensitive your sensor is to light. The more sensitive the sensor, the brighter your photo will appear!

ISO is a fantastic tool to help balance out your exposure after you’ve set your shutter speed and aperture for the scene you are shooting. Changing your ISO can often give you that little bit of brightening or darkening needed to really make your photo pop.

Luckily, the ISO settings are straightforward to understand. As the ISO number increases, so does the brightness of your photo. Most digital cameras will have ISO’s ranging from ISO100 to ISO6400. Higher-end camera models can have ISO ranges far beyond that.

Where To Find Your ISO Setting On Your Camera

Your ISO setting can be found within your settings preview. It’s most commonly labeled with the word ISO in a small box, followed by a number ranging from 100 to 6400 for example. This number is the ISO sensitivity. where-to-find-iso-setting

Digital ISO Vs. Film ISO

ISO in digital photography is a little bit different than is on film cameras. As you’ve now learned, the ISO setting in digital photography affects how sensitive the camera sensor is to incoming light. However, the ISO on a film camera is how sensitive the film is to light. The higher the films ISO, the larger the film grain will appear.

Now you may be thinking, “sweet, digital ISO means no film grain!”, and although you aren’t totally wrong, there’s a little more to the story. The caveat to ISO in digital photography is as you increase your ISO, you brighten your photo, but also increase the amount of noise in the image. I’ll talk more about noise later in this article.

With film cameras, the ISO cannot be adjusted since it’s the sensitivity of the physical film. With digital cameras, ISO can be easily adjusted up or down since it’s only affecting the sensor and not a physical roll of film.

What Does ISO Stand For

ISO stands for International Standardization Organization. This is an organization that standardizes the sensitivity of camera sensors across all brands (among many other things). Although certain camera sensors may have less noise at equivalent settings, the increase of brightness between ISO settings are the same across all cameras.

The Downside To  ISO

ISO can seem like the perfect camera setting. It’s straight forward to operate, there’s no fancy lingo, it just brightens your photo, what more could you ask for? Although those are all great perks of ISO in photography, there is an obvious downside you’ll discover at higher ISO’s.

As you increase your ISO, the more noise will appear in your photo. Noise looks a little bit like static on an old TV screen. It’s not very stylistic and can often be a little distracting. Not only that but it can also take away from the overall quality of your photo. Unfortunately, digital noise doesn’t quite have the same aesthetic effects as film grain, so it’s not commonly favored by most digital photographers.


This isn’t to say that you should be afraid of using a high ISO setting. It’s just important to remember that as you increase your ISO, so will the amount of noise in your photo. Try not to go crazy with your ISO when you could likely make adequate exposure adjustments with your shutter speed or aperture settings!

If you struggle to balance out your camera settings, then you need to check out my Manual Mode Cheat Sheet! It helps a ton to remember the pros and cons of each primary camera setting and works as a reference guide to make finding the perfect settings feel easy. Click here to get access to this FREE Cheat Sheet. Don’t miss out!

What Does Noise Look Like In A Photo

The amount of noise in your photo very slowly increases with each ISO setting. Below are some visual examples of how much noise appears in a photo from the lowest to highest ISO. Notice the significant loss in quality, particularly in the sky.


How To Use ISO In Photography

Learning how to use your ISO is an integral part of learning how to shoot in manual mode. It’s an essential tool to balance out the exposure in your photos but needs to be used purposefully.


It’s always best to keep your ISO setting as low as possible. It’s good to use a low ISO because it makes for a better quality image! If you’re shooting in daylight, there is rarely a reason to use a high ISO setting, even if you’re in the shade. You can always open up your aperture or slow down your shutter speed to lighten up your exposure instead. Remember, you want to keep your ISO setting low to reduce the amount of noise in your photo!

Now there are a few exceptions that you’re going to need a higher ISO for. For example, astro photography or very low-light scenes require you to use a higher ISO setting. Since there is such a lack of available light in these types of scenes, increasing the ISO helps you to utilize every last bit of light to help capture all the details possible.


ISO Quick Tips & Review

Your ISO Capabilities Will Depend On Your Camera: Depending on the camera you are using, the ISO range available to you can change. The standard ISO range is ISO100 to ISO6400, but with certain camera models, you can get up to something like ISO409600.

The Amount Of Noise Will Depend On Your Camera: Not all cameras have the same amount of noise at the same ISO settings. It all comes down to the actual sensor’s capabilities. Typically, higher-end cameras will have less visible noise at higher ISO’s compared to more entry-level camera bodies.

Don’t Be Afraid Of Using A High ISO: Sometimes, the scene you are shooting requires using a high ISO. Don’t miss out on a shot because you’re afraid of using the wrong ISO setting. Try to keep it as low as possible when you can, but don’t be scared to utilize it when the time comes.

ISO Is A Great Tool To Help You Balance Your Exposure: Once you’ve set your shutter speed and aperture, sometimes your photo still needs a little bit of help to get the perfect exposure. With your ISO, you can boost your exposure to a more even level.


Learning to use ISO in your photography is a big part of discovering how to nail your camera settings. ISO is a great tool to help balance out your exposure or give you a little bit of extra brightness in darker scenes. It’s crucial to remember that ISO not only brightens your photo, but it also can add noise to your image at higher ISO’s. You shouldn’t be afraid of this extra noise, but it’s essential to stay aware of and consider before you snap a photo!

The best (and easiest) way to remember ISO is with my Manual Mode Cheat Sheet! With the help of this handy cheat sheet, you’ll be able to choose your camera settings more confidently, instantly! I can’t recommend this one enough to you if you’re getting started with manual mode or are wanting to feel more comfortable with your camera settings. You can get access to my free manual mode cheat sheet by clicking here!

If you know someone who needs to boost their ISO knowledge, then make sure to share this post with them! If you enjoyed this article and want to keep up to date with more weekly photography content, make sure to subscribe to my weekly email newsletter!

Happy Shooting!


Article By

Brendan Williams

Hey, I'm Brendan! I'm a professional photographer and photo retoucher who has spent the majority of his career shooting or retouching outdoor lifestyle and social media campaigns for brands like G-Adventures, xoxo Bella, P&G, Fitbit, Chevy, Tourism California, and more. These days I primarily focus my efforts on this site, creating guides and tutorials that I wish I had earlier in my career. Each week I publish new tutorials on Photography, Photoshop, Lightroom, and Canva to help you unlock new skills and bring your creativity to new levels! Everything you learn here is backed by real experience, so you can finally skip the fluff and focus only on what matters.

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