Abstract: An objective lens comprises an iris diaphragm (D.sub.1) at the front and an optical assembly disposed behind the iris diaphragm. The optical assembly comprises a plano-convex front lens unit (G) with its plane surface facing the front of the lens, whereby the lens is suitable for use in media with different refractive indices (in practice, air and water). It further comprises a rear lens unit (G') adapted to apply the necessary correction to maintain abberations within reasonable limits and to achieve a required distance from the lens to the focal image plane. The invention is applicable, in particular, to discreet surveillance using a camera.

Abstract: An underwater still camera is disclosed having a watertight body with a back-loadable light-tight chamber, a lens, a shutter, a cocking lever for bringing the shutter to its cocked position, a push rod for releasing the shutter. Preferably the shutter, the cocking lever and push rod are all disposed outside the camera body. A retaining pawl is slidably and pivotally mounted inside the camera body and is cooperable with a toothed wheel carried by the transport spindle for blocking the rotation thereof under the control of a rotatably mounted intermediate spindle carrying sprockets engageable with perforation carried by a film and at least one stop or ratchet tooth cooperable with the retaining pawl. This arrangement permits use of a single film cartridge in an underwater camera originally adapted to receive a film pack.