camera obscura principle

An Illustration of the Camera Obscura Principle

I still remember the first day of my first photography class back in high school, the instructor started class with a description of what a camera is.  He said, a camera is nothing more than a box, with a hole in one side.  Sometimes, but not always, that hole has a lens in front of it and some way to block or admit light, a shutter.  Through this hole an image is projected on the far side of the box.  Often, but not always, that far wall has some kind of media on it to record the projected image.  These boxes are called camera obscura or “cameras” for short, from the Latin phrase “dark chamber” or “dark room”.

The principles behind camera obscura have been known for millennia.  One researcher has built a career around this idea and feels that there is plenty of evidence Paleolithic people were aware of the camera obscure principle (Paleo-Camera).  It is generally accepted that these people sought shelter in simple animal hide tents and huts in or near the entrances of caves.  Realizing that animal hides, especially those prepared with primitive tools, were sure to have small holes and cuts in them, and since they did not have windows to let in light, we can surmise that during inclement weather, the flaps of these primitive shelters were closed, darkening the inside and creating a “dark chamber”.  Oh, the stories that must have been told while watching upside down images of the landscape move across the opposite walls of these huts while a storm was raging outside.  Some of the evidence this researcher cites that this phenomenon was known is due to some cave paintings appearing to ignore the contours of the rocks they are painted on.  Much like images that are “projected” onto a rock or an uneven surface.

pinhole card projector

A pinhole card projector

On a modern day note, school children today in their science classes, learn how to observe the sun and solar eclipses with pinhole card projectors.  During an eclipse, or at any other time the sun is out, the user stands with their back to the sun, holding a piece of cardboard with a hole the size of a large pin in it.  If you hold this piece of cardboard right, you can project an image of the sun on a separate piece of cardboard laying on the ground (NASA JPL).  While pinhole card projectors have no walls to block out unwanted light like a dark chamber, this idea demonstrates that projecting an image is possible under many conditions if the source light is bright enough relative to ordinary surrounding ambient light.

Written records of the principles behind the camera obscura date back to circa 391 BCE when Mozi, a Han Chinese philosopher and the founder of Mohist School of Logic, proposed that a camera obscura image was projected upside down due to light traveling in straight lines from its source.  Aristotle, or one of his close followers, questioned how sun could project a circular image through a square hole about 330 BC.  In the same document, Aristotle also mentioned “crescent-shaped” projections of light through small holes.  Around the same time, it has been reported that Euclid mentioned that light travels in a straight line in his treatise Optics (circa 300 BC).  Over the next millennia, several other observations about images projected through an aperture were recorded.  In a 1038 essay, Maqalah-fi-Surat-al-Kosuf, reported that “The image of the sun at the time of the eclipse, unless it is total, demonstrates that when its light passes through a narrow, round hole and is cast on a plane opposite to the hole it takes on the form of a moon-sickle.”  It is believed that Franciscan friar Roger Bacon described and illustrated a camera obscura like device as early as 1292.

camera obscure principle, prague castle projection

An image of the New Royal Palace at Prague Castle, created at the attic wall by a hole in the tile roofing

By the 15th century we can assume that the camera obscura was beginning to be recognized as a drawing aid.  Mathematician and instrument maker Gemma Frisius coined the phrase “camera obscura” in his 1545 book De Radio Astronomica et Geometrica.  Also by the mid 1500’s, lenses and mirrors were being added to camera obscura.  Scientists and mathematicians who published studies describing the lens and mirror additions include, Gerolamo Cardano (1550), Giambattista della Porta (1558, 1589) and Daniello Barbaro (1567).  German mathematician Freiedrich Risner (1572) and Athanasius Kircher (1645) proposed and illustrated a portable camera obscura, complete with multiple lenses for use in the field.  By the early 1600’s Scientists and astronomers like Kepler (1604, 1611), Fabricius (1611), Galilei (1608) and Castelli (1612) had fitted telescopes to camera obscura to observe the sun.

Artists were using camera obscura as a portable drawing aid by the mid 1600’s.  There are written descriptions and diagrams of working models of the “dark chambers” with pinholes, multiple lenses with multi-images (up to 12 simultaneous images), interchangeable lenses and telescopic lenses.  Depending on how fast they worked, the artist was able to either draw an image with charcoal or ink, or, paint a picture.  Kind of like black & white or color film.  I propose that the only difference between today’s modern cameras and camera obscura circa 1650 is the actual material we use for media, and in fact, this is exactly what we do when we hand color photographs.

Photo Credits
Featured Image: New Royal Palace at Prague Castle By GampeOwn work, CC BY 3.0, Link
Camera Obscura Principle By Unknown – Public Domain, Link
A Pinhole Card Projector: NASA JPL

Please forgive me for not directly referencing my statements in my blog posts since it breaks up the flow of my thoughts and this is not intended to be a scholarly or referenced work.  Below are the sources for my statements that I assure you, are properly referenced.

by the way, not to be confused with: