Aperture Explained
What f-stops mean, why the numbers are 1.4, 2, 2.8, 4…, how aperture controls light and depth of field — and the best f-stop for every genre.
Aperture is the hole in your lens that lets light through. It does exactly two things: controls how much light reaches the sensor, and controls how much of the scene is sharp (depth of field). Everything else in photography is built on those two.
What the f-number means
The f-number is focal length ÷ aperture diameter. A 50 mm lens at f/2 has a 25 mm opening; at f/8 it's a 6.25 mm opening. Confusingly, smaller numbers = wider openings = more light. Each full stop doubles the light, and because the opening is a circle (area = πr²), the diameter must multiply by √2 ≈ 1.414 to double the area. That's why the scale looks like this:
| f-stop | f/1 | f/1.4 | f/2 | f/2.8 | f/4 | f/5.6 | f/8 | f/11 | f/16 | f/22 | f/32 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Light vs f/1 | 1× | 1/2 | 1/4 | 1/8 | 1/16 | 1/32 | 1/64 | 1/128 | 1/256 | 1/512 | 1/1024 |
| Relative DoF | 1× | 1.4× | 2× | 2.8× | 4× | 5.6× | 8× | 11× | 16× | 22× | 32× |
To trade one stop of aperture, you trade one stop of shutter or ISO. The free exposure calculator does these trades for you.
What aperture does to your photos
- Wide open (f/1.2–f/2.8): lots of light, thin depth of field, dreamy backgrounds — but only a sliver of the subject is sharp, and edges may be soft.
- Middle (f/4–f/8): the sharpest range on most lenses, still decent blur, enough light for most situations.
- Stopped down (f/11–f/22): maximum depth of field, but light drops fast and diffraction starts softening detail past f/8–f/11.
Best aperture by genre
| Genre | Typical aperture | Why |
|---|---|---|
| Portrait | f/1.8–f/2.8 | Background blur, subject separation |
| Landscape | f/8–f/11 | Front-to-back sharpness without diffraction |
| Real estate | f/8 | Room-wide sharpness, sharpest setting |
| Street / travel | f/4–f/8 | Balance of blur, sharpness and light |
| Sports / action | f/2.8–f/4 | Fast shutter needs light; keep some DoF for focus errors |
| Astro | f/1.4–f/2.8 | Maximum light for stars |
| Macro | f/8–f/16 | Thin DoF at high magnification; stop down or stack |
Related tools & guides
Depth of Field Calculator
See exactly how far sharpness extends at any f-stop, for your camera.
Open →Exposure Triangle Explained
Aperture, shutter and ISO as one system.
Read →Sharpest Aperture Guide
Diffraction limits computed for real cameras.
Read →Aperture FAQ
What does f-stop mean?
The f-number is focal length ÷ aperture diameter. Lower number = wider opening = more light, shallower depth of field.
Why are f-stops 1.4, 2, 2.8, 4?
Each stop doubles the light; area doubles, so diameter multiplies by √2 ≈ 1.414. The scale: 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32.
What's the sharpest aperture?
Usually f/4–f/8 on full frame — after that, diffraction softens pixels. See the diffraction guide for your camera's exact limit.
Does a wider aperture mean better photos?
Not automatically. It means more light and more blur — and less of the scene in focus, plus softer edges wide open.