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The sunstar or starburst effect in photography is a technique, where the sun or another bright object in the image is turned into a “star” by giving it those prominent and crisp rays that are radiating outwards from the center. Those bursts of light are the result of light bending around the edges of the aperture blades. At a narrow aperture, the blades of your lens close down to a tiny opening and create a diffraction of light that result in the prominent rays of light.
Sunstars are great for when you can’t make it to a location at the right time of day and have to shoot straight into the sun. Instead of giving up, turn the sun from an enemy into a friend and make it an interesting element of the image. Sunstars are also a good option for creating a strong focal point or compositional element if your image is lacking that little bit extra that draws the eye.
Now that I have explained what sunstars or starbursts are, here are a few elements that factor into creating a great and sharp looking sun:
Use a Small Aperture
I’ve already touched on the role aperture has in creating a sunstar, but the gist of it is that the smaller the opening, the better the resulting sunstar will look. On the other hand, if you shoot wide open, the sun is turned into a round, soft blob of light. Of course you could take it to the extreme and go as low as f/32 for a very dramatic starburst, but with the sweet spot of your lens probably being around the f/8 area, you wouldn’t want to go that narrow due to the light diffraction creating softer and lower quality images.
Therefore, my go-to aperture for creating sun stars is f/16. While it does create a great burst of light, I avoid loosing too much sharpness. Of course, a smaller aperture also means a slower shutter speed and especially if you shoot in lower light conditions, I definitely recommend bringing a tripod for a stable exposure.
Find a Defined Edge
While you can most definitely create sunstars with the sun high up in the sky, I noticed that I tend to get better, more defined sunstar results when the sun is partly blocked by something. To play peek-a-boo with the sun like this, anything from the side of a building to the horizon at sunrise or sunset work, but the harder edged, more defined your obstruction is, the better the resulting star. You’ll have to move around with your camera a bit to find the spot where the sun is partly obstructed, but believe me, the results will be worth it.
Avoid Lens Flare
Using a hard edged obstruction to create a more defined sunstar also comes with the bonus that the annoying light flares you usually get when shooting straight into the sun are greatly reduced. If there are any left over, use the good old trick of taking two exposures, one a regular one and one with your finger straight over the sun to block out all the flares. Then, merge the two in Photoshop.
In the image below from Dead Horse Point in Utah, I removed all lens flare but the one big flare going across the image. Somehow, I kind of like it, but that’s just personal preference.
The Lens Matters
You have heard me preach over and over again that gear doesn’t matter – much. Creating sunstars is one of those instances where having the right lens can make a huge difference. This is because how many points or rays of light your sunstar exhibits is entirely dependent on the number of aperture blades your lens has. If the lens has an even number of blades, it will produce the same number of rays as there are blades. If, on the other hand, your lens has an odd number of aperture blades, you will be rewarded with double that number of points in your star.
One of my lenses, a Sigma 10-20mm unfortunately only has 6 aperture blades and creates a very weak, funny looking sun star. Thus, if I want to create a really awesome looking sun, I usually grab my Sigma 18-50 with 7 aperture blades to create a prominent, crisp looking sun with 14 light spikes.
Look for that Pure Sunlight
If the sun is half hidden behind a cloud or obscured by haze, fog or mist, your sunstar will be either nonexistent or turn into a soft, muddy and generally less defined blob of light. This often happens around sunrise or sunset, when hazy clouds tend to linger around the horizon. It doesn’t matter if there are clouds in other parts of the sky, just make sure that the immediate area surrounding the sun is clear blue sky to create a crisp and well defined star.
And a quick last note: The starburst effect is not limited to the sun of course. Any light source that is significantly brighter than the surrounding area can be starred in the right conditions. After sunset, try starring street lights or even the moon!