Ever looked at a photo and wondered why the subject pops while the background melts away? If you’ve typed “what does aperture mean” into a search bar lately, you’re not alone. With new camera releases, upgrades to phone lenses and a surge in people learning photography for social media, aperture is suddenly a hot topic across the UK. Here I explain what aperture means, why it matters, and how to use it to take better pictures today.
What does aperture mean — the simple definition
Aperture refers to the opening in a camera lens that lets light pass through to the sensor or film. Think of it like the pupil of your eye: it gets bigger or smaller to control how much light enters.
How aperture is measured: f-numbers or f-stops
Aperture is expressed as an f-number (or f-stop), such as f/1.8, f/4 or f/16. Smaller f-numbers mean a larger opening (more light); larger f-numbers mean a smaller opening (less light). That’s slightly counter-intuitive, but it’s the convention used worldwide.
Why photographers care: exposure and depth of field
There are two big reasons aperture matters: exposure and depth of field. Exposure is about brightness; bigger apertures let in more light so you can shoot in darker settings without raising ISO or slowing the shutter speed. Depth of field is about what’s in focus — a shallow depth of field isolates a subject, while a deep depth of field keeps most of the scene sharp.
Real-world example: portrait vs landscape
For portraits you might choose a wide aperture such as f/1.8 to blur the background and make the subject stand out. For landscapes you’ll often use f/8 to f/16 so foreground-to-horizon detail remains sharp.
How aperture interacts with shutter speed and ISO
Aperture is one corner of the exposure triangle. Change aperture and you usually adjust shutter speed or ISO to keep the same exposure. Want to freeze motion but still have a blurred background? You’ll need a wide aperture and a fast shutter speed — that might mean boosting ISO a touch.
Practical examples and mini case studies
Case study — wedding reception (low light): A UK wedding photographer might use f/1.8 to capture candid moments without flash. That gives a soft background and keeps shutter speeds high enough to avoid blur.
Case study — street photography in London: Using f/5.6–f/8 balances subject isolation with enough depth for environmental context, making images feel grounded in place.
Common aperture settings and what they do
Here’s a quick guide to common f-stops and when to use them.
| f-stop | Effect | When to use |
|---|---|---|
| f/1.2 – f/2 | Very shallow depth of field, lots of light | Low light portraits, artistic blur |
| f/2.8 – f/4 | Shallow to moderate depth of field | Portraits, isolating subjects |
| f/5.6 – f/8 | Moderate depth of field, sharpness | Street, travel, everyday landscapes |
| f/11 – f/16+ | Large depth of field, less light | Landscapes, architecture |
Depth of field made visual
Want a quick test? Stand roughly two metres from a friend. Shoot at f/1.8 and then f/11 with the same framing. The subject stays in focus, but the background transforms. That demonstrates exactly what aperture does.
Lens type matters: prime vs zoom, and maximum aperture
Prime lenses typically offer wider maximum apertures (f/1.4, f/1.8) than many zooms. That makes them favourites for low-light and portraits. Lenses advertise their maximum aperture (e.g. 24-70mm f/2.8) — a constant f/2.8 zoom is pricier but more flexible in dim conditions.
Smartphone aperture — what’s different?
Many phones have fixed, small physical apertures, relying on software and sensor technology to simulate shallow depth of field. Recent flagships use multiple lenses or adjustable apertures to get closer to DSLR-like control. For deeper technical background see Wikipedia on aperture and for practical tips check a manufacturer guide such as Canon’s explanation.
Common mistakes and how to avoid them
Mistake: Always shooting wide open. Yes, a wide aperture looks great for portraits, but many lenses are softer at their widest setting. Try stopping down one or two stops for crisper results — so f/1.8 might become f/2.8 or f/4.
Mistake: Forgetting diffraction. Very small apertures like f/22 can reduce sharpness due to diffraction, so only use them when you truly need maximum depth of field.
Quick workflow tips for UK photographers
- Set aperture first for creative effect (depth), then adjust shutter and ISO for exposure.
- In low light, prefer wider apertures and moderate ISO to keep noise under control.
- Use aperture priority mode (A or Av) to quickly test depth-of-field ideas while you learn.
Comparison: aperture effects at a glance
This short comparison helps you decide quickly on the day.
| Goal | Suggested aperture | Why |
|---|---|---|
| Isolate subject (portraits) | f/1.4–f/2.8 | Creates creamy bokeh and separates subject |
| Everyday sharpness (street) | f/4–f/8 | Balanced sharpness and light control |
| Maximum depth (landscape) | f/8–f/16 | Foreground to background detail |
Practical takeaways — what to try next
- Run a simple test: shoot the same scene at f/1.8, f/4 and f/11 to see differences.
- Use aperture priority mode to focus on creative choices while the camera handles exposure.
- When buying glass, check the maximum aperture: wider is better for low light and creamy backgrounds.
Further reading and trusted resources
For technical depth see Wikipedia’s aperture page. For practical, camera-maker advice check a manufacturer’s guide like Canon UK.
Final thoughts
Aperture is one of those simple-sounding ideas that unlocks real creative control. Once you know what aperture means — how it shapes light and focus — you can choose the look you want. Try the small experiments above, and you’ll see instant improvements in your photos. Happy shooting (and a little curious experimenting never hurt).
Frequently Asked Questions
Aperture is the opening in a lens that controls how much light reaches the camera sensor. It also affects depth of field — a wide aperture gives a blurred background, while a small aperture keeps more of the scene in focus.
For portraits, photographers often choose a wide aperture like f/1.8 to f/2.8 to blur the background and emphasise the subject. If you need more of the scene in focus, stop down to f/4 or f/5.6.
No — a smaller f-number (e.g. f/1.8) means a larger lens opening, so more light enters. Larger f-numbers (e.g. f/16) mean a smaller opening and less light.