Today’s Wonder of the Day was inspired by Charis from Houston, TX. Charis Wonders, “What is a pinhole camera, and how does it work?” Thanks for WONDERing with us, Charis!
Do you enjoy reminiscing with friends and family members as you look through old photo albums? It's so much fun to look back and remember good memories from years ago.
Twenty years from now, you might look back at photo galleries on social media accounts, such as Facebook and Instagram, rather than photographs in books. And there will probably be hundreds, if not thousands, of photos to enjoy.
Thanks to advanced technology that has put a digital camera inside every smartphone, it's much easier to capture memories by snapping photos of the daily events of our lives as they occur. All of that advanced technology can make us forget how old — and simple — the basic science behind photography really is.
The most basic kind of camera is called a pinhole camera and it consists of just a few things: a light-proof box, film, and a pinhole.
Sometimes known as a camera obscura or a dark chamber, a pinhole camera works very simply. The pinhole acts as a lens, letting in light emitted by whatever scene it happens to be pointed at.
Since the pinhole is tiny and lets in very little light, you have to keep the pinhole camera pointed at the scene for a much longer time than a normal camera. Typical exposure times can vary from as little as five seconds to several hours. Eventually, every point of light coming through the pinhole will expose a tiny portion of the film, creating an inverted and reversed image on the film.
Since the tiny pinhole forces every bit of light it lets in to expose a tiny part of the film, it usually results in fairly clear, crisp images once the film is developed. In a regular camera, a lens is used to create a much larger hole that lets light in, so that exposure time is greatly reduced.
The basic science of photography at work in the pinhole camera (known as the rectilinear propagation of light) was recognized as early as the 5th century B.C. in China. Greek mathematician Euclid elaborated on the basic principles over 2,300 years ago. Leonardo Da Vinci was also fascinated by the simplicity of the pinhole camera.
Today, pinhole cameras are often made at home as part of science projects. One popular use is for safely viewing solar eclipses, since you can view the event indirectly through a pinhole camera.
Professional pinhole cameras are still manufactured and are popular with professional photographers who want to add a unique tool to their photographic arsenal. Because of their small size, pinhole cameras are also often used for covert surveillance.