Have you ever taken a photograph of a streetlight at night and noticed that it appears to have long, pointed rays extending from it? The same effect can sometimes be seen in films and videos, particularly when bright lights are included in a dark scene.

This star-shaped appearance is known as a diffraction spike, and it’s caused by the way light behaves as it passes through a camera lens and its aperture. Understanding how diffraction spikes form can help photographers and video creators produce striking visual effects without relying on digital filters.

What Are Diffraction Spikes?

Diffraction spikes are bright lines that appear to extend from concentrated light sources in photographs and videos. They’re particularly noticeable around streetlights, decorative lights and other small, bright objects against a darker background.

The effect occurs because light behaves like a wave. When light passes through an aperture, it spreads and interferes with itself, producing patterns that can become visible in the recorded image.

The shape of the aperture plays an important role in determining the appearance of these patterns. In photography, the resulting star-shaped effect is often called a starburst or sunstar.

How Do Aperture Blades Create Starbursts?

Most camera lenses use a mechanical aperture made from several overlapping blades. These blades form an opening that controls how much light reaches the camera sensor.

When the aperture is stopped down, the edges of the blades can create diffraction patterns that appear as rays extending from bright light sources. The number and arrangement of the blades influence the number and appearance of the rays.

For a conventional aperture with straight, evenly arranged blades, an even number of blades generally produces the same number of prominent spikes. An odd number of blades generally produces twice as many spikes. This happens because diffraction patterns from opposite, parallel edges can overlap.

For example, a conventional six-bladed aperture may produce six prominent rays, while a seven-bladed aperture may produce fourteen. The exact appearance depends on the optical design and shape of the aperture, so real lenses don’t always produce perfectly defined patterns.

Why Does Aperture Size Matter?

Diffraction spikes often become more noticeable when a lens is stopped down to a smaller aperture opening. For example, photographing a streetlight at f/11 may produce a more pronounced starburst than photographing the same light at f/2.8.

This is partly because the aperture blades form a more defined opening when the lens is stopped down. However, the effect depends on the lens design, and not every lens produces equally strong starbursts.

It’s also important to remember that using a very small aperture can reduce overall image sharpness because of diffraction. The best setting is therefore a balance between the appearance of the starburst and the sharpness you want elsewhere in the image.

How to Create Starburst Effects in Your Videos

If you want to experiment with diffraction spikes, start by including a small, bright light source in your composition. Streetlights, decorative bulbs and distant city lights can all work well.

Try using a narrower aperture, such as f/8 or f/11, if your lens and lighting conditions allow. Compare the results at different aperture settings to see how the appearance changes.

For video recording, remember that changing the aperture also affects exposure. If you’re filming at a fixed shutter speed and frame rate, you may need to adjust the lighting, ISO or neutral density filtration to maintain the exposure you want.

It’s also worth using a tripod or another stable camera support when filming in low light.

Diffraction Spikes Versus Lens Flare

Diffraction spikes and lens flare are sometimes confused because both can appear around bright light sources. However, they’re caused by different optical effects.

Diffraction spikes result from the way light behaves around aperture edges or other obstructions in the optical path. Lens flare is primarily caused by unwanted reflections and scattering within the lens system.

Flare can appear as bright spots, streaks, rings or a general reduction in contrast. Both effects can be used creatively, but understanding the difference makes it easier to produce the result you’re looking for.

Can You Add Starbursts in Editing?

If your footage doesn’t contain natural diffraction spikes, you can create a similar appearance using video editing software. Many applications offer glow, light-ray or starburst effects that can be applied to bright areas of an image.

These effects provide more flexibility because their appearance can be adjusted after filming. However, digitally generated starbursts may not look identical to the optical patterns created by a real lens.

For creators looking for a natural result, experimenting with the lens aperture during filming is often a useful starting point.

Using Starbursts for Creative Effect

Starburst effects can add visual interest to night-time footage, city scenes, product videos and cinematic sequences. They can also help establish a particular atmosphere, especially when combined with carefully chosen lighting and composition.

Like many visual effects, they tend to work best when used deliberately rather than simply because they’re available. Understanding why diffraction spikes appear gives you another creative option when planning your shots.

And if you’re creating a cinematic night-time sequence or atmospheric montage, the right music can help bring the visuals together. Explore the RouteNote Licensing music and sound effects library to find audio that complements the mood of your footage.