Imagine you have an empty cylindrical can, like a coffee can or a soda can. On one side of the can, you make a very tiny hole, with something small like a sewing needle.
Say you're outside on a sunny day, and you want to capture an image of a tree using your can pinhole camera. You position the can so that the pinhole side is facing the tree.
Even though your can camera doesn't have any lenses or complex parts, the light from the tree still manages to go through that tiny pinhole, almost like the pinhole is a tiny eye looking at the tree.
Inside the can, on the opposite side of the pinhole, you place a piece of photographic paper or film. When the light from the tree goes through the pinhole, it creates an image on that paper or film. But here's the interesting part – the image appears upside down!
So, if you were to peek inside the can later on, you'd see an upside-down picture of the tree on the paper or film.
That's the essence of a pinhole camera using a can as an example. It's a straightforward way to create a camera that uses a tiny hole to let in light and form an inverted image on the other side, with no need for lenses or any complicated equipment. And the longer you leave the photographic paper or film in the camera, the more interesting your images can be!