Monday, May 21, 2012

Leonardo da Vinci Describes Pinhole Projection

After watching the eclipse yesterday, I was intrigued by the history of observing pinhole projections. I mentioned Aristotle, who said "sunlight travelling through small openings between the leaves of a tree, the holes of a sieve, the openings wickerwork, and even interlaced fingers will create circular patches of light on the ground." We observed this -- see the four little crescent projections of the partially obscured sun:


Many other scientists (or natural philosophers) of early times also discussed various types of pinhole projections. Da Vinci wrote, in Codex Atlanticus:
"I say that the front of a building -- or any open plazza or field  -- which is illuminated by the sun has a dwelling opposite to it, and if, in the front which does not face the sun; you make a small round hole, all the illuminated objects will project their images through that hole and be visible inside the dwelling on the opposite wall which should be made white; and there, in fact, they will be upside down, and if you make similar openings in several places in the same wall you will have the same result from each. Hence the images of the illuminated objects are all everywhere on this wall and all in each minutest part of it. The reason, as we clearly know, is that this hole must admit some light to the said dwelling, and the light admitted by it is derived from one or many luminous bidoes. If these bodies are of various colors and shapes the rays forming the images are of various colors and shapes, and so will the representations be on the wall."

No comments: