The Ultimate Guide to Understanding Your Camera ISO Settings

Are you tired of blurry, grainy photos? Are you struggling to understand the ISO settings on your camera? If so, you’re not alone friend. ISO can be one of the most confusing aspects of photography, but it’s also one of the most important. The good news is that it’s also actually one of the easiest settings to choose on your camera. Understanding how to use ISO properly can take your photos from amateur to professional level. In this ultimate guide, I’ll break down everything you need to know about ISO settings, including what it is, how it affects your photos, and how to use it to your advantage. So grab your camera and let’s get started!

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What is ISO and how does it work?

ISO is essentially the camera’s sensitivity to light. It’s represented by a number, usually ranging from 100 to 6400 (and beyond in some cameras), with lower numbers indicating lower sensitivity to light and higher numbers indicating higher sensitivity to light. The lower the ISO number, the less sensitive your camera is to light and is best used in bright light scenarios—think a beautiful bright sunny afternoon. The higher the ISO number, the more sensitive your camera is to light and is best used in lower light situations. Scenes like indoor natural light, or even darker churches and reception halls might require a higher ISO.

It’s important to understand that ISO doesn’t actually affect the amount of light entering your camera—that’s still controlled by the aperture and shutter speed. Instead, ISO adjusts the camera’s sensitivity to that light. For example, if you’re shooting in a low-light situation, you can increase the ISO to make your camera more sensitive to the available light, allowing you to take brighter photos without having to slow down your shutter speed or widen your aperture. The main downside to increasing your camera’s ISO is that ISO also controls the amount of grain (or digital noise) you see in your images. The higher the ISO, the more grain that will be visible. More visible grain can make your photos appear less sharp and less detailed. That’s why it’s important to choose the right ISO setting for your specific situation.

How to choose the right ISO for your photos

Choosing the right ISO for your photos depends on a variety of factors, including the available light, the desired effect, and the subject you’re photographing. As a general rule, you should aim to use the lowest ISO setting possible for the situation at hand in order to minimize noise and maximize image quality. And when in doubt, try ISO 400. This is a great beginner setting when you are a bit unsure where to start. The best news about ISO is that it is the first part of the exposure triangle you choose, and if your lighting doesn’t change too much while you are photographing then you won’t need to change it at all during that shoot.

When I’m shooting a session in bright daylight, for example, I usually set my ISO to 100 or 200 and then don’t think about it for the rest of the 1-hour session. Unlike your aperture and shutter speed, ISO does not need to be constantly changed and adjusted unless there are fairly big changes in your lighting. If I were to step inside a house during the session though, I might need to increase my ISO to 400 or 800 depending on the available light and brightness of the room. I always try to keep in mind that increasing my ISO too much can result in significant noise, so I am always balancing the need for more light with the need for image quality.

Examples of ISO settings in different lighting conditions

Here are some examples of ISO settings in different lighting conditions:

– Bright daylight: ISO 100-200

– Overcast day/bright indoors: ISO 400

– General Indoor lighting: ISO 800

– Low-light situation: ISO 1600-3200

– Nighttime: ISO 6400 or higher

Of course, these are just general guidelines and you may need to adjust your ISO settings based on the specific situation at hand. Like when taking outdoor night shots I prefer a lower ISO with a higher f-stop and I use a tripod to get a clear image.

To help you get a better sense of how ISO settings affect your photos, I have created an ISO cheatsheet for you to download and bring with you.

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Ways to minimize Noise

As mentioned earlier, higher ISO settings can result in more noise or grain in your photos. Noise is essentially the digital equivalent of film grain—it’s the random speckling of color that appears in areas of your photo that should be smooth. While some amount of noise is inevitable when shooting at high ISO settings, there are ways to minimize it.

One way to minimize noise is to be sure you are properly exposing your image when using a high ISO. If you need to bring up the exposure in post production you will see more of the noise. Whereas if you create a well exposed image, even with a high ISO, the noise will not be as noticeable to the naked eye. So be sure when increase ISO to only do so if you know your image will be properly exposed. Another way to minimize noise is to use noise reduction software in post-processing. Adobe Lightroom has just updated their software and has an amazing “denoise” option that makes a world of difference for images with high ISO and digital noise by smoothing out the noise without sacrificing the important aspects of your photo. I’ll be doing a full post and video on this very soon.

It’s important to note that some amount of noise is usually acceptable depending on the situation. For example, if you’re shooting in a dimly lit reception venue and the only way to capture the moment is to use a high ISO setting, a bit of noise may be preferable to a completely blurry or dark photo. Always remember that special moments are more important than “perfect” imagery.

Common misconceptions about ISO settings

There are a few common misconceptions about ISO settings that are worth addressing:

Higher ISO settings always result in better photos: While increasing your ISO can make your photos brighter in low-light situations, it can also result in more noise or grain. It’s important to balance the need for light with the need for image quality.

Lower ISO settings are always better: While it’s generally true that lower ISO settings result in less noise, using too low of an ISO setting in low-light situations can result in underexposed photos or cause a lot of camera shake. It’s important to choose the right ISO setting for the specific situation at hand.

Auto ISO is always the best option: While auto ISO can be a convenient option, it’s the VERY FIRST setting I suggest my students turn off on their camera. Manual control of your ISO setting is always preferable.

ISO seems to be one of the most confusing aspects of photography, but it’s also one of the most important. Understanding how to use ISO will improve your images dramatically. Understanding how ISO works within the exposure triangle will change how your control your camera and will enhance your photography. If you use ISO properly you’ll be well on your way to taking stunning photos in any lighting situation. So grab your camera and start experimenting—the possibilities are endless!




  • I am happy that I found you as my first teacher and your teaching are clearly understood especially for a beginner like me .

    • Steffen, I am so glad that this has helped you understand ISO better. As always, feel free to reach out via email or the facebook group for any questions—I am always happy to chat photography!


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I am a professional photographer & photo educator. I’m here to share with you my best (and easiest) tips and tricks for taking amazing photos. I’m sharing years of knowledge as a teaching artist to help you find a way to share your unique point of view with the world. Welcome to The Photo Method.

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