Worldwide Pinhole Camera Day

By Matt Young
Rural scene in upstate New York
A rural scene in upstate New York taken with a pinhole camera. The photograph was exposed in about 1972 using a Praktiflex FX with a set of extension tubes and Kodak Tri-X film. The depth of field is virtually infinite, which is to say equally poor at all object distances.

Today is World Pinhole Camera Day, a fact I just learned on NPR yesterday morning. Which is somewhat surprising, because years ago I did some original research on the pinhole camera. Below the fold,…

Cover of the journal, The Physics Teacher

… the cover of the issue of The Physics Teacher in which I published an article on pinhole optics. (The picture seems sharper than the picture above, possibly because I used a longer focal length, but such data are largely lost to antiquity.)

Graph showing the normalized resolution limit of the pinhole camera as a function of image distance.
Resolution limit of the pinhole camera as a function of image distance, using normalized variables. s is the radius of the pinhole.

You may also see a pared down version of my research in the Wikipedia article on the pinhole camera. The heart of the paper is the figure, below left, showing in normalized variables the resolution limit of the pinhole camera as a function of image distance (colloquially but incorrectly called focal length in the paper). The pinhole camera is best focused when the pinhole is, in effect, a Fresnel zone plate with a single zone.

Since this is primarily a biology blog, I will mention that the nautilus has a pinhole eye.