The Krasnogorsk 3 is a clockwork Russian 16mm mirror-reflex movie camera manufactured at the KMZ factory (Krasnogorskij Mechanicheskij Zavod which translates to Krasnogorsk Mechanical Plant) near Moscow. It was still being manufactured up until the early 1990s.

Most later K-3s have an M42x1 lens mount (also known as a Zenit or Pentax screw mount), although there are some older cameras which use the same bayonet mount as earlier Krasnogorsk movie cameras. The standard lens for the K3 is the Meteor-5 17 to 69mm F1.9 Zoom lens.

The camera uses 100ft(30m) reels of 16mm film, the film can be either single or double perforated, when fully wound the camera will run through about 5m of film (approximately 30 seconds of footage at 24 frames per second) in one go. The camera can be run at 8, 12, 16, 24, 32, or 48 frames per second.