Aperture in photography: f-stops, depth of field and light

Aperture controls the size of the opening inside the lens. It changes both how much light reaches the sensor and how much of the scene appears sharp.

Why smaller f-numbers mean a wider opening

Values such as f/1.8 or f/2.8 represent wide apertures. They let in more light and usually create a shallower depth of field. Values such as f/8 or f/11 let in less light and generally keep more of the scene in focus.

Use aperture for a visual reason

A portrait may benefit from a wide aperture to separate the subject from the background. A landscape may benefit from a smaller aperture to keep several planes sharp. The best aperture is the one that supports the image you want, not the lowest or highest number your lens allows.

For a deeper explanation, see our guide to depth of field.

Aperture changes the other settings too

If you close the aperture, you may need a slower shutter speed or higher ISO to keep the same exposure. These trade-offs are easier to understand through the exposure triangle.

Use Photo Coach to connect setting and result

The camera settings feature in Photo Coach can suggest an aperture based on the scene and creative effect you describe, while the AI critique helps you judge whether the depth of field actually works in the finished image.