The camera obscura uses telescope lenses of 4 to 12 inches diameter, depending on your budget, room size, and focal length. For example, one instrument I designed included an 8-inch lens and a 12-inch mirror. My instruments are custom designed to meet your viewing needs and your building.
The instrument can include 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 are motor driven. The observer controls all motions using a group of switches mounted at the edge of the viewing table. A fully adjustable instrument uses 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 are mounted in a welded steel framework insulated with fireproof ½ inch plywood. The attractive turret is attached to the steel and plywood frame and usually is covered in copper. A chain-drive rotates the turret while ball bearing clamps secure the turret against wind loads. The outside scene is imaged through a large plate glass window in the turret.