What causes a starburst
A starburst, often called a sunstar, is the pointed star shape that appears around a bright, small light source such as the sun or a streetlamp. It is mainly caused by diffraction, which happens when light bends as it passes the edges of the aperture blades inside your lens. The smaller the opening, the more pronounced the effect.
Because it comes from the lens, you do not need special filters. You need the right aperture, a suitable lens, and a light source positioned well in the frame.
Camera settings
- Aperture: use a narrow aperture. Values around f/16 to f/22 are commonly recommended, and some photographers start as small as f/11. Test your own lens, because the look differs from lens to lens.
- ISO: keep it low, such as ISO 100, to limit noise. Small apertures reduce the light, so you will often need a slower shutter.
- Shutter speed: adjust it to expose the scene properly. In daylight this is often easy, but at night it may become several seconds.
- Support: use a tripod and a remote release or self-timer when exposures are slow.
- Focus: focus on the main subject as usual. The star shape is formed by the aperture, not by focus.
There is a trade-off. Very small apertures, beyond roughly f/22 on many lenses, can soften the whole image because diffraction also reduces fine detail. If sharpness matters, try a few apertures and compare.
Aperture blades and number of points
The number and shape of blades matters. In general:
- Lenses with straight blades tend to produce clean, defined rays, while rounded blades often give weak or no starbursts.
- With an even number of blades, the number of points usually matches the blade count, so eight blades give eight points.
- With an odd number of blades, the points usually double, so nine blades give eighteen points.
Different lenses at the same aperture can give very different results, so if the effect matters to you, check sample images for the lens before buying.
Placing the light source
How you frame the light is as important as the settings:
- Partly hide the light. Position the sun or lamp so it peeks around an edge, such as a tree branch, building, mountain ridge or horizon. Showing only part of the source often gives well-defined rays while avoiding a blown-out centre.
- Keep the source small. A tiny, bright point works better than a large, diffuse glow.
- Adjust your position. Moving a few steps changes how much of the light is visible and how strong the rays are.
- Check the playback. You often cannot see the full effect in the viewfinder or live view, so review the image on the screen and adjust.
Sun starbursts and safety
Pointing a camera at the sun is common practice for this effect, but avoid looking directly at the sun through an optical viewfinder, since it can damage eyes. Use live view or the rear screen, and keep sun exposure to short periods, particularly with long lenses. Partly hiding the sun, as above, also lowers the intensity.
Night lights
Streetlights, car headlights, shop signs and city lights can all become stars at small apertures. Dusk is a good time to try it; see twilight photography. Use a tripod, a low ISO and a long exposure, and keep an eye on the histogram so the brightest lights do not clip too far. Night scenes are also a good time to try the same aperture choices described in our guide to infrared photography at night, where lamps appear in very different colours.
Lens and glass care
Dust and smudges on the front element can turn small specks into distracting flare blobs, especially when a strong light is in the frame. Clean your lens before shooting, and consider removing a filter, since stacked glass can add ghosting and extra reflections. A lens hood helps control stray light, though it will not remove all flare.
Common problems
- Rays look weak: try a smaller aperture or a lens with straighter blades.
- Image is soft: the aperture may be too small, so open up a stop.
- Flare and ghosts: change your angle, clean the lens, or remove filters.
- Blown-out centre: hide more of the light, or reduce exposure slightly.
- Star is lopsided: check that the light is small and clear of other bright objects.
Phones
Phone cameras generally have fixed apertures that are quite wide, so they do not make strong starbursts on their own. Some phones can produce small light streaks from bright lights, and editing apps can add stars, but the look differs from the lens-based effect. Getting a real starburst usually calls for a camera with an adjustable aperture. This topic is different from photographing actual stars in the night sky, which depends on long exposures and dark skies.
Related guides
If you like creative light effects, our infrared nature photography guide covers another way to give landscapes an unusual look.
FAQ
What is the best aperture for a starburst?
Many photographers use roughly f/16 to f/22. Going smaller can soften the image, so test the options on your lens.
Why do some lenses make better starbursts than others?
The shape and number of the aperture blades decide how defined the rays are and how many points appear.
How do I get the flash photography effect?
That is a different look. A starburst comes from diffraction around a small light source, while a flash look comes from lighting the subject directly. Starbursts are not a flash technique.
Can I shoot star photos on an iPhone?
A phone can take night-sky pictures in its night modes, but that is not the same as the starburst effect. For sunstars you need an adjustable aperture.