Nikon D800 | Tokina AT-X 16-28mm F2.8 Pro FX | ISO 400 | 1/640 sec | F2.8 Photo: Abby Ferguson

Understanding shutter speed, aperture and ISO can be overwhelming for beginner photographers. Even once you comprehend the terms and settings on their own, knowing when to use specific values for each can be confusing. After all, each of those settings controls something different, and putting it all together is a lot.

It's not feasible to provide specific numbers that you should use for a given situation, since that's dependent on the amount of light in the scene and your gear. However, below you'll find tips on identifying a general ballpark of which shutter speed, aperture and ISO you should use to achieve the visual effect you want.

Shutter speed

A fast shutter speed was necessary in this situation to freeze the action of the surfer. Nikon D800 | Nikon 80-200mm F/2.8D ED IF AF-S | ISO 100 | 1/5000 sec | F3.2 Photo: Abby Ferguson

Shutter speed, which you can learn more about in our video on the topic, is one of the fundamental properties of exposure. A slow shutter speed lets in more light, making your image brighter, while a fast shutter speed lets in less light, making your image darker (assuming the rest of your settings stay the same). It's important to note that shutter speeds are fractions of a second, though some cameras only display the denominator. Smaller denominators (such as 1/20) are slower shutter speeds, while larger denominators (such as 1/2000) are fast shutter speeds.

Beyond controlling how much light your sensor is exposed to, shutter speed also impacts how movement appears in your photographs. As a result, choosing a shutter speed comes down to whether there is movement in your scene and how you want it to look.

Slow shutter speeds will result in blurred movement, which can be useful for conveying a sense of time. You often see slow shutter speeds used when photographing rivers or waterfalls, traffic at night or creative images of people moving. Fast shutter speeds, on the other hand, freeze movement. They are ideal for highlighting action. That's why sports and wildlife photographers typically use fast shutter speeds.

In this image, the slightly blurred movement in the subject's hands helps show more action than a perfectly still image would. Sony a7 III | Sony Vario-Tessar T* FE 24-70mm F4 ZA OSS | ISO 1000 | 1/40 sec | F4 Photo: Abby Ferguson

Broadly speaking, shutter speeds slower than 1/60 sec are considered slow, while those higher than that are considered fast. However, what constitutes fast and slow shutter speeds in a given situation depends on multiple factors, the most important of which is the speed of the movement.

Fast movement requires faster shutter speeds to freeze movement. For extremely fast-moving subjects, such as a race car, a shutter speed of 1/2000 sec or more is necessary. Slower movement allows for a slower shutter speed while still stopping movement in the image. For example, a baby crawling across the floor may only need a shutter speed of 1/125 sec to freeze the movement.

It's also important to know that working with slow shutter speeds is likely to cause camera shake or blur across the entire image from the camera's movement during exposure. So, when using slow shutter speeds, it's best to put your camera on a tripod or another sturdy surface to avoid an image that is entirely blurry.

Aperture

The background could have been distracting in this image and wasn't important for adding context, so I chose a shallow depth of field to keep attention on the cat. Nikon Z6 III | Nikon Z 35mm F1.4 | ISO 400 | 1/125 sec | F3.2 Photo: Abby Ferguson

Aperture is the second fundamental property of exposure, which you can learn more about in our video explainer. It refers to the size of the opening in the lens, which determines how much light enters the camera. A larger opening lets in more light, making the image brighter, while a small opening lets in less light, making the image darker.

Aperture is one factor that impacts depth of field, or how much of a scene is in focus. A wide open aperture, which is named with a small F-stop number such as F1.8, will result in a shallower depth of field, or only a small amount of the scene in focus. A small aperture, which is named with a large F-stop number like F22, will provide a deep depth of field, or most of the scene in focus.

For this landscape, I wanted everything reasonably in focus, so I used small aperture in order to produce a deep depth of field. Nikon D800 | Tokina AT-X 16-28mm F2.8 Pro FX | ISO 320 | 1/800 sec | F10 Photo: Abby Ferguson

A shallow depth of field is ideal for keeping the focus on your subject and blurring out distracting elements in the background. It is typically used in portraiture and macro photography. Deep depth of field is useful when everything in the scene is important, such as landscapes or architectural photography.

ISO

If you look carefully at the dark sky, you can see a fair amount of noise. Fujifilm GFX100RF | F4 | 1/60 sec | ISO 12,800 | Processed in Adobe Camera Raw Photo: Mitchell Clark

Finally, there is the often-misunderstood setting: ISO. This setting determines how much your camera amplifies the signal of the light hitting its sensor, thereby making the image brighter or darker. Lower ISOs mean its boosting the signal less, adding less lightness, and higher ISOs boost it more, making a low-exposure image appear brighter. A high ISO is helpful in situations where you can't capture a lot of light through your exposure settings, such as at night or in dark interior spaces. A low ISO is best for conditions with lots of light, such as a bright and sunny day.

ISO itself doesn't cause noise, but capturing less light will result in noisy images compared to bright, well-lit situations. So, if image quality is most important, you'll want to prioritize getting enough light so that you can use lower ISOs.

There was enough light in this scene that I could avoid noise. Sony a7 III | Sony Vario-Tessar T* FE 24-70mm F4 ZA OSS | ISO 1000 | 1/40 sec | F4 | Processed in Adobe Camera Raw Photo: Abby Ferguson

How aperture, shutter speed and ISO work together

While all three settings have some sort of visual effect (even if indirectly), they all impact how dark or bright your photographs will be. Choosing your shutter speed, aperture and ISO is a balance of getting a correct exposure and achieving the look you want for motion, depth of field and noise.

When determining which numbers to use, it's important to first decide if motion or depth of field is most important or if you need to balance the two. If motion is the critical feature, select your shutter speed and then dial in your aperture and ISO to obtain an appropriate level of brightness. If depth of field is the priority, set your aperture to whatever gives you the look you want, then use shutter speed and ISO to correct your brightness level. Sometimes you need to find a happy middle ground with those two exposure settings and use ISO to round out how bright the image is.