In this quick tip, we are going to take a look at star filters and see how easily and quickly we can one at home in a few minutes for free.
As you can see from the image below, the effect of the star filter is very interesting. It basically creates star patterns on the places where there is a bright point of light. The sun, car lights, street lights, traffic lights and much more "activate" the filter.
The number of the streaks we have depends of the type of pattern of our filter. You can get such filters from eBay for $5 to $15. That being said, creating your own lets you customize the pattern and it's more fun!
Creating the filter
To create the filter, you need to scratch a pattern on one of the sides of the plastic using the pin and the ruler. The ruler helps create the straight lines needed for the process. The plastic can be obtained from various sources. My favorite source is old cases for cassette tapes or cds, break off the front and start from there. If you don't have one laying around the house, go buy a CD-R and sacrifice the case.
The number of streaks depends of the type of the pattern. Below you can see a few images that represent different types of patterns. You'll also see how the star is going to look once you use the filter in a real life situation.
You can see that without the filter and when using open aperture your lights will look like spots. In order to get the pattern, you need to put your star filter in front of your lens.
This is our first pattern. As you can see, if we scratch straight lines onto the plastic, we are going to get an anamorphic type of flare in our image. This is pretty helpful if you are looking for a type of spacey effect.
This is the next option using the same first pattern. The best part is that you can simply rotate the plastic 90 degrees and get a completely different result.
Diagonal Intersecting Lines
Here we have a more complex type of pattern as you can see. If you create such a pattern you are going to get a 4 streaks star effect.
Diagonals and Horizontals
Moving on, you can see that if we add some horizontal straight lines, our pattern is
going to look pretty complex. The final flares will have six streaks.
Diagonals, Verticals and Horizontals
This is our final pattern. Now we have 8 light streaks and we get some pretty nice star patterns. That doesn't mean that you can't add more lines and make star patterns with 12 and more streaks. You just need to be more precise.
Another idea is to create two similar patterns on different pieces of plastic and stack them on top of each other. By offsetting their rotation, you can get a huge number of streaks and different patterns.
I hope that this quick tip and introduction to star filters gives you an idea how these filters work and how to make one. This is an old school trick that was used a lot in the past.
This technique also works for video cameras. You can easily attach the star filter using tape to attach it to your lens body or camera body, or you can use a filter ring to filter holder to create a better system.
I'm looking forward to seeing what you come up with. If you shoot some nice pictures using a star filter, feel free to post them in the comments.