What does f/1.8 mean? Aperture explained with examples

The short version

Aperture is the size of the opening in the lens. It is written as an f-number such as f/1.8 or f/8. A small number means a wide opening. A wide opening lets in more light and makes the background softer.

Why smaller looks bigger

The f-number is a ratio, not a size, so it feels backwards. f/1.8 is wider than f/8. Each full step in the usual series (1.4, 2, 2.8, 4, 5.6, 8, 11) halves or doubles the light.

What you will notice

• f/1.4 to f/2.8: bright, soft background, good for portraits and dim rooms. Less of the scene is in focus.
• f/4 to f/5.6: a balance for everyday shots.
• f/8 to f/11: more of the scene is sharp, common for landscapes and buildings.

Where to find yours

Your camera or phone stores the aperture in the photo file. Drop the photo on Shutterlune and open Camera details to see it. Then read what the rest of the EXIF data means.

Phones often report a fixed aperture such as f/1.8, because the lens does not change. Some phones also simulate background blur in software.

Example

A portrait at 50mm, f/1.8, 1/250 s and ISO 200 has a soft background and a fast shutter to keep the subject sharp. The same scene at f/8 would need a slower shutter or a higher ISO to stay as bright.