Origami optics

Folding up lens to make short lenses have the same abilities as a long focal length lens. [Link]

Sports photogs aren't compensating for something by swinging gigantic, monopod-mounted lenses; they need the focal length. Focusing and zooming on outfielders usually means glass far from the camera body, but not so when using so-called "origami optics," flat lenses being researched at UCSD Jacobs School of Engineering that use internal reflection to achieve long focal lengths. Only the outer ring actually captures the image, while the others bounce it around before depositing light onto the film or sensor.