Fact 1: Certain candies come wrapped in foil and this foil frequently has several small holes in it.
Fact 2: If a small hole is placed over a smartphone camera lens, the camera gains the apparent ability of being able to focus equally on all subjects in front of the lens.
Now that we know those two facts, let’s use a peanut butter cup wrapper to give our smartphone better close-focus abilities!
I’ve set up a few small dinosaur friends on a table. Every dinosaur is a different distance away from the lens, so the camera (operator) will have to choose which dinosaur will be in focus.
Here’s what it looks like when we focus on the green dinosaur, which is about 8 inches from the lens:
If the camera (operator) focuses the lens further into the background, then the blue dinosaur will come into focus, but this means that the green dinosaur will not be sharply focused.
Here’s what it looks like when we focus on the blue dinosaur, which is about 24 inches from the lens:
It is not possible for the smartphone lens to focus equally on the green dinosaur and the blue dinosaur.
How can all the dinosaurs come into focus?
We’ll need to use a peanut butter cup!
First, unwrap the peanut butter cup from its foil and look for tiny holes in the foil.
Center the candy-wrapper pinhole over the smartphone lens and bring it close enough to the lens so that an image appears on the smartphone screen.
All three dinosaurs are now all the same level of focus, but that focus is not particularly sharp.
In pinhole-photography terms, all three dinosaurs are now “equally unsharp”.
By pressing the pinhole right up over the smartphone lens, we’re creating a smaller opening for the light to enter the lens, also called an “aperture” or “f-stop”.
The small aperture means that more of the image appears to be “in focus”, relative to using a larger aperture on the same lens.
Khan Academy has a video that explains why a smaller camera aperture results in more apparent focus. https://www.khanacademy.org/partner-content/pixar/virtual-cameras/virtual-cameras-1/v/optics1-final
There is an ideal pinhole size for any given smartphone camera and it’s a good idea to try out several pinhole sizes to see which results in the sharpest (unsharpest?) image.
Below are the results of various other pinhole sizes: 1mm, .35mm, .25mm, .1mm, and .05mm
Unedited footage of all the pinholes, plus some bonus candy-wrapper pinholes: https://youtu.be/UFMNVIJ1bsk