Have you ever taken a photo outside, and the settings are perfect, but noticed that when you moved into some shade, the photos come out dark? In cases like this, where you feel as though you don’t want to change your aperture or shutter speed because they are nailed down perfectly, ISO can save the day.

If you’re trying to get an understanding of basic camera settings down, ISO should be one of the settings you focus on. Broadly, you can think of ISO as essentially light (or exposure) compensation. It’s very simple. If your photo is too dark, you can just bump up your ISO, and instantly see a brighter exposure than before. The technical name for this setting is “International Organization of Standardization,” and mechanically, its job is to determine your camera sensor’s sensitivity to light when it opens. So, turning ISO up essentially makes your sensor more sensitive to light particles, thus increasing the amount of light recorded by the sensor when capturing an image.

Now, although this initially sounds like a great tool for a photographer, it can introduce other complications. ISO may improve lighting in many cases and save an image from being poorly exposed, but it also introduces something called “noise,” into a photo. Have you ever noticed a grainy discoloration that looks almost like some type of pixelation in a photograph? This is noise, and when it gets bad enough, it can completely destroy the quality of a photo. Thankfully, modern-day DSLR cameras do an excellent job of reducing noise introduced by ISO, and post-processing (editing) techniques are also available to further reduce the impact of this noise. Nonetheless, the presence of noise should be noted when you change your ISO setting while taking pictures.

There are a lot of interesting situations in which the use of ISO drastically improves the conditions for exposure and can really turn a sub-par photo into a stellar one. A great example of this can be found in wildlife and other action photography. When shooting a photo of a bird, for instance, you’re going to want to use a small aperture to get plenty of in-focus detail, and a fast shutter speed, to reduce the amount of blur when the animal moves. Both of these settings, unfortunately, reduce the amount of light captured. Thankfully, ISO is available to fix this. Bumping your ISO up can even out the exposure and give the photographer the ability to capture the bird in mid-air, and with crisp detail, while still gathering enough light for a balanced exposure.

Using what you’ve read in my last two photo tips (shutter speed & aperture), try to use this additional setting and see what you can create! It can be extremely useful in many situations but beware of the noise it will introduce if bumped up too high! In my opinion, the best way to understand this setting is to play around with it in manual mode (M on the dial) while also making shutter speed and aperture adjustments. In my next photo tip I plan to talk about tying together all three of these settings together and discussing the entirety of the exposure triangle!