(((This is the last of a four-part series on the camera obscura == bruces)))
"Another notable improvement came in 1568 when Daniele Barbaro, a Venetian nobleman, described a camera obscura outfitted with a lens and diaphragm. This forerunner of the aperture could be made progressively smaller so the image would become ever sharper. With continuing improvements in optics, the camera obscura no longer needed a large, stationary room to create an image.
"In 1572 Friedrich Risner constructed a small hut that could be carried around the countryside and used to make topographical drawings. Camera obscuras began to shrink in size and improve in optical quality. By 1657, camera obscuras were small enough to be carried under one arm.
"During the latter half of the 17th century, they proliferated across Europe, with uses as varied as painting, architectural drawing and spying.
"As remarkable as the instruments were, they didn't fully satisfy the needs of artists. While canvas painting is a vertical pursuit, many artists preferred to sketch a scene on a laptop pad. In 1676, Johann Christoph Sturm, a professor of mathematics at Altdorf University in Germany, introduced a reflex mirror. Mounted at a 45 degree angle from the lens, the mirror projected the image to a screen above. This elegant configuration is at the core of modern single lens reflex cameras.
"In 1685, Johann Zahn, a monk from Wurzburg, solved the final piece in the optical puzzle. Improving upon Sturm's design, he introduced lenses of longer and shorter focal lengths. Scenes as wide as a landscape or as close as a portrait could be viewed with a simple change of lens.
"He also painted the interior of his camera obscura black to avoid internal reflections. Excepting a mechanical shutter, Zahn's invention was the prototype for today's camera. Yet it would be over one hundred and fifty years before the camera obscura and photosensitive chemicals were combined to make permanent photographs."