lens

Chris Marquardt: Through the Round Lens

http://chrismarquardt.com/about.php

Episode 1421

The topic for today's Photo segment is why lenses are round and not rectangular like the images. Chris says that a lens is essentially a projector, and all projectors cast a circular image. What makes the image square is the sensor, though the original Kodak actually printed round images. It's also better to have round lenses because round motion can convert to linear motion more easily.