Aperture is one of the three pillars of photography exposure — alongside shutter speed and ISO — and it's one of the most powerful tools for controlling both the look and the brightness of your images. Understanding aperture is the key to achieving that beautiful blurred background look, as well as sharp landscapes where everything is in focus.
What is Aperture?
Aperture refers to the opening inside your lens that controls how much light passes through to the sensor. It's measured in f-stops — such as f/1.8, f/4, or f/16. Confusingly, a smaller f-number means a larger opening, and a larger f-number means a smaller opening.
Wide Apertures (f/1.2 – f/2.8)
A wide aperture lets in a lot of light and creates a shallow depth of field — meaning only a thin slice of your image is in sharp focus, while the background blurs into smooth bokeh. This is ideal for portrait photography, product shots, and low-light shooting. Lenses with wide maximum apertures (like f/1.8 or f/1.4) are often called "fast" lenses.
Narrow Apertures (f/8 – f/16)
A narrow aperture lets in less light but creates a deep depth of field — meaning more of the scene, from foreground to background, is in sharp focus. This is ideal for landscape photography, architecture, and any situation where you want everything sharp. The trade-off is that you'll need a slower shutter speed or higher ISO to compensate for the reduced light.
The Sweet Spot
Most lenses perform at their sharpest somewhere in the middle of their aperture range — typically around f/5.6 to f/8. At very wide apertures, sharpness can soften slightly at the edges, and at very narrow apertures, diffraction can reduce overall sharpness. For general shooting, f/5.6–f/8 is a reliable starting point.
Aperture and Exposure
Aperture works together with shutter speed and ISO to control exposure. Opening your aperture by one stop (e.g. from f/4 to f/2.8) doubles the amount of light — so you'd need to increase your shutter speed or lower your ISO to maintain the same exposure.
Keep Learning
Once you've got aperture dialled in, check out our Simple Guide to Shutter Speed and our Simple Guide to ISO to complete your understanding of the exposure triangle. And if you're ready to put it all into practice, browse Ted's range of mirrorless cameras online or visit your nearest Ted's store.