Short answer
There is no single best f-stop for night photography. The right choice depends on whether you are handheld or on a tripod, and on whether you want a wide, shallow look or sharpness from front to back. As a rough guide:
- Stars and the Milky Way: as wide as your lens allows, often around f/1.4 to f/2.8.
- Handheld night street scenes: commonly f/1.8 to f/4, depending on the lens and how much depth of field you need.
- Cityscapes and landscapes on a tripod: often f/5.6 to f/11 for sharpness across the frame.
Treat those ranges as starting points rather than rules. Check your results and adjust.
What the f-stop does at night
The f-stop sets how wide the lens opens. A smaller number such as f/1.8 means a wider opening and more light. Each full stop (for example f/2 to f/2.8) halves or doubles the light reaching the sensor. At night, more light lets you use a faster shutter speed or lower ISO. The trade-off is depth of field: wide apertures give a thin zone of sharp focus, and many lenses are slightly soft or show more vignetting and distortion at their widest setting.
Is f/2 enough? Is f/2.8 good for low light?
Both are good for many night situations. Fast lenses like f/1.8 or f/2 are very helpful handheld, because they let you keep shutter speed fast enough to avoid blur. An f/2.8 lens is workable for night streets and, with a high enough ISO and a short exposure, for stars. It collects less light than f/1.8 or f/1.4, so you will need a higher ISO or longer shutter speed to match. An f/4 lens can work too, particularly on a tripod where you can expose for longer, but it is more limited handheld and for stars.
Modern cameras handle higher ISO reasonably well, so a slower lens is not a deal-breaker. It simply moves the compromise elsewhere. If you want a faster lens on a budget, a 35mm or 50mm f/1.8 prime is a common first purchase.
Wide open for stars
For the night sky, the camera must gather as much light as possible in a limited exposure time, because stars trail if the shutter stays open too long. A lens opened to f/2.8 or wider is the usual choice. Our article on Milky Way photography covers the full setup.
The 500 rule
A common starting point for star exposures is the 500 rule: divide 500 by your lens focal length to estimate a maximum shutter speed in seconds before stars begin to trail. A 20mm lens gives roughly 25 seconds. On a crop-sensor camera, use the full-frame equivalent focal length. The rule is a rough guide only. With high-resolution sensors, stars can trail visibly at the suggested time, so many photographers choose a somewhat shorter exposure. Test and zoom in to check.
Handheld street work
On the street, you need a shutter speed fast enough to avoid camera shake and subject movement, and a depth of field deep enough to keep a moving subject in focus. Many people settle on f/2 to f/4 and a high or Auto ISO. If you are zone focusing, a slightly smaller aperture such as f/4 gives more margin for error. See night street camera settings for a fuller starting set of values. Our complete night photography guide covers how aperture fits in with shutter speed and ISO.
Tripod work: stop down for sharpness
With a tripod you can use a slow shutter, so you do not need a wide aperture to avoid blur. Most lenses are sharpest somewhere around f/5.6 to f/8, and a smaller aperture also increases depth of field for landscapes and buildings.
Stopping down further has a limit. At very small apertures, such as f/16 to f/22, diffraction softens fine detail. The point at which this shows depends on the lens and sensor, but going to the smallest aperture rarely helps.
Smaller apertures also turn bright point lights into starbursts, which can be a pleasing effect for streetlamps. Stopping down is also a way to lengthen exposures for smoothing water or moving cars.
What f-stop do most photographers use?
There is no standard answer, but people tend to pick one of two approaches. Handheld, they shoot near wide open to protect shutter speed. On a tripod, they stop down to a middle value for sharpness. If you are unsure, f/2.8 handheld and f/8 on a tripod is a reasonable pair to test with.
Focus at wide apertures
At f/1.8 or f/2, depth of field can be only a few centimetres at close range. Use Live View zoom to check focus, and take several frames with slightly different focus if the subject can be recaptured.
Quick decision guide
- Handheld and moving subject: wide to moderate aperture, such as f/1.8 to f/4, with Auto ISO.
- Handheld and static subject: wide aperture, lower shutter speed, brace the camera.
- Tripod and static scene: f/5.6 to f/11, low ISO, long shutter speed.
- Stars: widest aperture that gives acceptable corners, around f/1.4 to f/2.8.
Common mistakes
- Shooting wide open without checking edge sharpness.
- Using f/22 and losing detail to diffraction.
- Raising ISO when a wider aperture or tripod was available.
- Forgetting that lighting can change what is needed. See night photography lighting for ways to give your scene more light.