Today’s Question: I am wondering if the lens you used [when capturing a photo with a sunburst effect] didn’t contribute to the result you obtained?
Tim’s Quick Answer: Yes, indeed. The shape and number of the aperture blades in a lens can have a significant impact on the starburst effect you can create. That, in turn, means lens choice is a consideration when you want to be able to include a starburst effect in a photo.
More Detail: Today’s question is a follow-up to a previous question about how I created a sunburst effect in a photo where the sun was in an open area of sky rather than being positioned against a solid object. You can see the photo in question on my Instagram feed here:
First of all, the number of aperture blades in the lens has an impact on the starburst effect. In short, the more aperture blades, the more rays in the starburst. In addition, with an even number of aperture blades the starburst effect will have the same number of rays as there are aperture blades. With an odd number of aperture blades, the starburst effect will have twice as many rays as there are aperture blades.
The shape of the aperture blades also has an impact on the effect. The blades of the aperture are intending to form a perfect circle by overlapping the blades. If the aperture blades are very straight, that “circle” will be more of an obvious polygon formed by straight edges. If the aperture blades are more curved, the aperture will be closer to a perfect circle.
Curved aperture blades are often preferred by photographers because those blades contribute to circular bokeh effects, rather than bokeh that takes on a polygonal shape. In addition, however, with curved aperture blades you will generally get a less distinct starburst effect.
In other words, lenses with aperture blades that are relatively straight (rather than curved) will generally produce a more pronounced starburst effect. And lenses with a greater number of aperture blades (especially with an odd number of aperture blades) will produce a starburst effect that has more rays, and therefore will look more “sparkly”.