The Modern Camera Obscura
The camera obscura designs George built used telescope lenses of 4 to 12 inches diameter, room size, and focal length. For example, one instrument George designed included an 8-inch lens and a 12-inch mirror. George's instruments were custom designed to meet the viewing needs and the building.
The instrument included a fixed or adjustable lens and mirror that focuses the desired image on a horizontal or vertical surface viewed in a darkened room. Adjustable optics were motor-driven. The observer controlled all motions using a group of switches mounted at the edge of the viewing table. Fully adjustable instruments George would build used motors to tilt the mirror, rotate the turret, and focus the lens on objects from infinity to as close as 100 to 400 feet. Other switches control the lighting and darken the room.
The field of view is set by the lens focal length and the table diameter, which is generally 10° to 20°.
The optics were mounted in a welded steel framework insulated with fireproof ½ inch plywood. The attractive turret was attached to the steel and plywood frame and usually was covered in copper. A chain-drive rotated the turret while ball-bearing clamps secured the turret against wind loads. The outside scene is imaged through a large plate glass window in the turret.