Aperture, measured in f-stops (like f/1.8, f/5.6, or f/16), refers to the size of the opening in a camera lens that controls the amount of light hitting the sensor. It significantly impacts three main aspects of a photograph: exposure, depth of field, and sharpness. Understanding aperture settings gives photographers control over these elements, allowing them to achieve different visual effects that suit the creative intent of the shot.

Exposure: Aperture settings directly affect the exposure, or brightness, of an image. A wider aperture (represented by a lower f-stop, such as f/1.8) lets in more light, which brightens the image and is particularly useful in low-light conditions, such as indoors or during dusk. A narrower aperture (represented by a higher f-stop, like f/16) restricts light, resulting in a darker image, which is beneficial in bright environments to avoid overexposure. Balancing the aperture with shutter speed and ISO allows for a well-exposed image even in challenging lighting situations.

The following images were taken using:
1: Focal Length: 28mm
2: Shutter Speed: 1/5 second
3: ISO: 100
4: Aperture: f/1.8 to f/7.1
Click thru the images below to see the effect of decreasing the aperture, while keeping the other settings unchanged. Notice, as the aperture reduces, the brightness reduces and the depth of field increases (the numbers in the back become clearer). Which image below did you like the most? Share in the comments below.

Depth of Field: One of the most visually impactful effects of aperture is depth of field, or the range of the image that remains in sharp focus. A wide aperture (small f-stop) creates a shallow depth of field, meaning only a small portion of the image is sharply focused, while the background is beautifully blurred. This effect, often called “bokeh,” is popular in portrait photography as it isolates the subject and draws attention to them. In contrast, a narrow aperture (larger f-stop) creates a greater depth of field, where most of the scene is in focus. This setting is ideal for landscapes, architecture, or any photograph where the photographer wants both the foreground and background to appear sharp and clear.

Here is an image taken with a pretty wide open aperture (f/1.8), producing an image with a very shallow depth of field. Notice how the chairs in the background are blurry. I also changed the lighting settings to create a nice warm setting. Share your thoughts in the comments below.

Image Sharpness: Aperture also influences sharpness and the performance of the lens. Most lenses perform best around the middle of the aperture range, typically between f/5.6 and f/11, where images appear the sharpest and with minimal distortion. At very wide apertures (like f/1.4), lenses might show slight softness at the edges and increased “vignetting,” where the corners appear darker than the center. Similarly, very narrow apertures (such as f/22) can lead to diffraction, where the image loses overall sharpness due to the scattering of light. We will look into this in more detail when we talk about the Exposure Triangle.

By adjusting the aperture, you can control these effects, shaping the mood and focus of each image. A wider aperture can create a dreamy, intimate portrait, while a narrower aperture can capture the grandeur of a landscape with equal clarity throughout. Ultimately, the effect of aperture on a photograph is multifaceted, enhancing the creative possibilities available to photographers.

NEXT: Understanding ISO