If you already own an interchangeable lens camera, you can make a pinhole lens in five minutes.
How a Pinhole Camera Works
Light is reflecting off of every object around us. Our eyes focus these light rays so that we can see the details of where this light is reflecting from. Similarly, a camera lens focuses these light rays onto a flat sensor or piece of film. Without lenses, the light reflecting off objects would hit the camera's sensor from every direction, causing the sensor to record brightness but no shape or detail.
By allowing light to hit a flat sensor from a single pinhole, you are forcing all the light to hit the sensor from one single point, perpendicular to the image plane, creating a somewhat focused image.
In theory, the smaller the hole, the sharper the image, but at a certain point, diffraction will become an issue, and a smaller hole will create a softer image. Learn more about the math behind choosing your pinhole size here.
How To Make a Pinhole Lens
You can purchase pinhole lenses, but before you do, you should try to build your own. This is the easiest way to build a pinhole camera
Step 1. Drill a hole in the center of your camera's body cap.
Step 2. Tape a single piece of aluminum foil over the hole
Step 3. With a pin or needle, poke a small hole in the center of the foil.
Check out the video above to see it in action.
I'm going to be experimenting with more pinhole cameras in the future. If anyone has any tips on how to get a sharper image let me know.
If you want a really clean hole I recommend having someone laser cut the the hole for you. That way you get the opening as close to a perfect circle as possible.
I taped black foil over the drilled hole, I found the smallest needle I could for the pinhole. The black foil helps keep reflections down. The smaller the hole the sharper the image, this one turned out great. Shot with a Sony A7II.