Diffraction Blur in Imaging

Because of the wave nature of light, the image of a point is not a point but a blob whose size depends on the wavelength and the f-number of the lens. In the Diffraction Blur article, I compute this blob profile, including  the off-axis case.

Blurring (nonzero blob size) is not caused by the edge of the iris. It is caused by the iris' elimination of the good, far-from-the-axis rays. Larger apertures result in a larger spread in path-length differences for the various rays striking the sensor at points away from the ideal image point. This increases the destructive interference at these points, resulting in a sharper image.

Simple Solution to Monkey and Coconuts Problem

This article describes a simple solution to the well-known monkey and coconuts problem. This is accomplished using base-5 arithmetic.