In my office lobby, we have a very neat light display that hangs from the ceiling. It’s a cube of LEDs that can be programmed to show colours, patterns, or even recognizable visuals if viewed from the right angle. I was in the lobby when the main lights happened to be off, and it isolated the display from the background that much more. I decided to get a shot of the LEDs out of focus with my 50mm lens at the widest aperture, as that gives a nice effect of the dots all stacked over each other. A neat thing about a wide aperture being out of focus is that the points of light in the out of focus area expand and take on the shape of the aperture. Since my lens has a lot of blades in the aperture to give it a smooth circular curve, the out of focus elements have a smooth circular shape in the middle.
Interestingly enough, an aperture doesn’t need to be a circle, that (or something close) just works best for photography. If you have a lens that goes to a wide enough aperture (generally a prime lens of 1.8 or lower), you can even cover up the front with a different shape, and the out of focus elements will take that on.
I got this with my 50mm, shooting at 1/160 of a second and f1.8, ISO 200.