Playing With Lenses: Something on Starbursts

Sunday, 24 December 2017

Something on Starbursts

I love starbursts! On sinking sun, on a night street light or just a little glitter in the background.
You might know that there are at least two common ways to create the starburst effect in a photo.

First one is by using a Cross Screen filter, reviewed in an earlier blog on the Hoya CS. These typically give you longer rays, and the ability to choose the angle of the rays.

Starburst by using Hoya CS Filter

The other ways to create starbursts is by selecting a very small aperture, where the rays are created by light diffraction in the corner between two aperture blades.

What is less known is how to control the number of rays within your starburst. One corner between two blades creates two rays. One stronger one in the corner where two blades meet, and one less stronger one at the opposite side. The more blades in a lens, the more corners between blades, the more rays you will see in the photo.

If you have an even number of blades, the ray on the other side will overlap with the ray caused by the opposite corner of two different blades. If you have uneven blades, there is no opposite corner, so no rays to over lap. As a result, you can use the following formula's:

If an even number of blades, the number of rays is equal to the number of blades
If an uneven number of blades, the number of rays is double the amount of blades

The sharpness of the blades is also a good test to measure the sharpness of the lens when aperture is mostly closed.

Some Samples: