"Now there's a bare branch in front of the sun image, blowing in the wind. Here's a whole array of them through the pegboard. You can see that through every hole is a different image. Every hole is a slightly different viewpoint. From image to image, the changes are very slight, but from the right-hand side of the board to the left-hand side of the board, the images are very different. In fact, you can't see much similarity between what's on the right-hand side of the board and what's on the left-hand side of the board.
"So this really gave me an insight into the question, what is depth of field? A pinhole image is always pretty much in focus, and even if you move the board back and forth, everything is pretty much in focus: the branch that is very near and the sun that is very far away are both in focus.