Use these tips to always select the correct aperture

When you’re starting to move away from shooting in totally auto mode to either Aperture Priority or fully manual mode, it can be difficult to know which f-stop is the right one for each scene. It’s often a creative decision, but not always, as it depends on the subject, how much light you need, and the focal length of the lens.

Understanding aperture is part of the cornerstones of photography, and will help you to make deliberate creative decisions that elevate your photography. In this video, Julia Trotti explains how she decides the best aperture for her portraits.

What is aperture?

First a quick reminder: Aperture is the opening inside your lens that controls the amount of light reaching the camera sensor. It’s measured in f-stops. A lower f-stop number (e.g., f/1.2) means a larger aperture, allowing more light into the sensor and creating a shallower depth of field. A higher f-stop number (e.g., f/5.6) indicates a smaller aperture, allowing less light and increasing the depth of field.

In practical terms, using a larger aperture (lower f-stop) results in a brighter image with more background blur, while a smaller aperture (higher f-stop) delivers a darker image with more elements in focus.

Fast and slow apertures

You may hear lenses described as “fast” or “slow” in relation to their aperture. A “fast” lens refers to one with a larger aperture (e.g., f/1.2), which allows more light to hit the sensor, enabling faster shutter speeds. In contrast, a “slow” lens, such as one with an aperture of f/5.6, requires slower shutter speeds to achieve the same exposure due to the reduced amount of light entering the camera.

Tips for choosing the right aperture

1. Consider Lighting Conditions

Aperture is essential for getting the correct exposure for the lighting conditions. For example, if you’re shooting outdoors on a bright, sunny day, you’ll likely want to use a smaller aperture like f/5.6 or f/8 to avoid overexposing your photo. In contrast, low-light conditions, such as indoor or nighttime photography, require larger apertures like f/1.8 or f/1.2 to let in more light and prevent underexposure.

2. Balance Aperture with Shutter Speed and ISO

Aperture isn’t the only factor in achieving correct exposure. It works in conjunction with your shutter speed and ISO settings. If you’re aiming for a creative effect, such as a blurry background (bokeh), you might choose a wide aperture, regardless of the lighting. From there, adjust your shutter speed and ISO to balance the exposure.

For example, if you’re using a large aperture of f/1.4 to capture soft bokeh, you can increase your shutter speed or lower your ISO to prevent overexposure, especially in bright conditions. The relation between aperture, shutter speed and ISO is known as the Exposure Triangle.

3. Depth of Field Control

Depth of field, or the portion of the image that’s in sharp focus, is directly impacted by aperture size. A large aperture (f/1.2 to f/2.8) creates a shallow depth of field, which is great for portraits or wedding photography, where you want your subject to stand out against a blurred background. On the other hand, a small aperture (f/5.6 or higher) produces a deep depth of field, keeping more of the scene in focus. This is ideal for landscape or architectural photography.

4. Subject Matter Determines Aperture

The type of photography you’re doing can help dictate your aperture choice. For example, if you’re photographing a large group, such as at a wedding, using a large aperture like f/1.4 could result in some people being out of focus. To avoid this, use a smaller aperture (e.g., f/5.6 or f/8), which expands the plane of focus and ensures everyone is sharp.

5. Creative Effects with Aperture

One of the most noticeable creative effects achieved with aperture is bokeh—the beautiful blur in the out-of-focus areas of a photo. A large aperture not only lets in more light but also enhances the size and smoothness of the bokeh. Conversely, using a smaller aperture keeps more background detail in focus, which can be useful when you want to highlight the environment or setting in your photo.

6. Know Your Lens’ Limitations

Not all lenses can achieve the same aperture range. Prime lenses generally have larger maximum apertures (like f/1.2 or f/1.8), while zoom lenses tend to offer smaller apertures. If you find yourself struggling to get enough light or depth of field with your current kit lens, you might consider investing in a lens with a wider aperture for greater creative control.

---