Understanding aperture

Aperture is one of the three pillars of exposure, alongside shutter speed and ISO. It refers to the size of the opening in a lens through which light passes to reach the sensor. Aperture is measured in f-stops, and the scale can seem counterintuitive at first: a smaller f-number means a larger opening, and a larger f-number means a smaller one.

The f-stop scale

The standard full-stop aperture scale runs: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, and f/32. Each full stop halves or doubles the amount of light reaching the sensor. Most modern cameras also allow you to set aperture in third-stop or half-stop increments for finer control.

Aperture and depth of field

The most visible creative effect of aperture is depth of field: the range of distance in a scene that appears acceptably sharp.

• Wide apertures (f/1.4 – f/2.8) produce a shallow depth of field, isolating your subject from the background with smooth, creamy blur known as bokeh. This is a favourite technique for portrait photography, where separating a person from a busy background draws the viewer's eye to their expression.
• Mid-range apertures (f/5.6 – f/8) tend to be the sweet spot for most lenses, offering the best balance of sharpness across the frame while still providing some background separation. Many street photographers and documentarians work in this range.
• Narrow apertures (f/11 – f/22) produce a deep depth of field, keeping both foreground and background in sharp focus. This is essential for landscape photography and architectural shots, where you want every element in the scene to be tack-sharp.

Aperture and lens sharpness

Every lens has an aperture at which it produces its sharpest results, sometimes called the critical aperture. This is typically two to three stops down from the lens's maximum aperture. For a 50mm f/1.8 lens, peak sharpness often falls around f/4 to f/5.6. At very narrow apertures like f/22 or f/32, an optical phenomenon called diffraction begins to soften the image; stopping down further does not always mean a sharper photo.

Aperture in practice

The aperture you choose depends on what you want to communicate in the image. A wide-open portrait at f/1.4 feels intimate and dreamlike. A landscape at f/16 feels expansive and detailed. The best way to develop an intuition for aperture is to study real photographs and see the difference for yourself.

Explore photos by aperture on shutterdial

Use shutterdial to browse real photos from Flickr filtered by aperture. See how different f-stops shape the look and feel of an image:

• Portraits at f/1.4 – shallow depth of field, beautiful background blur
• Portraits at f/2 – slightly more context, still creamy bokeh
• Landscapes at f/5.6 – the lens sweet spot; balanced sharpness
• Landscapes at f/11 – deep focus, front-to-back sharpness
• Landscapes at f/16 – maximum depth of field for sweeping vistas
• Macro at f/13 – fighting thin depth of field up close

Or start a custom search and dial in any combination of focal length, aperture, and shutter speed to discover what's possible with your camera.