Gun Camera, 16mm, Gun Sight Aiming Point, Type M-4A US Navy

Gun Sight Aiming Point (GSAP) Cameras are electrically-operated motion picture cameras which were used across US Army Air Force and US Navy fighter and attack aircraft during WWII and the Korean War. These cameras were designed to record results obtained in aerial and ground gunnery training and for producing visual records of aerial combat.  By the end of WWII, the AN-N6 GSAP cameras were the standard for this application. This example, the M-4 camera (12v), was commonly used by US Navy aircraft and was an earlier generation which was superceded by the AN-N6 (24v).  

The GSAP camera, using an A-6 cartridge containing 50 feet of 16mm film and a 35mm lens, was typically mounted inside of the wing or nose, or in the cockpit attached to the reflector gun sight (using an "erector assembly" with a 90 degree prism to align the sight).  It was preferred to install it on the gun sight in order to capture the sight's illuminated reticle in the film's images, thereby providing evidence of aiming accuracy.  The camera was operated through the firing circuit (for guns, rockets, and bombs) as well as through an independent camera circuit.  When properly installed and harmonized with the weapon system, the camera recorded all phases of action during the burst of gun fire at all points were the fire converges. 

The knob at the top above the label selects the shutter speed: 16, 32, or 64 frames per second. The knob below the label is the footage indicator knob, adjustable from 0-49 ft. This knob is to be set to the same footage that is indicated in the "unexposed footage" window of the film cartridge.

The 35mm lens is a Bell & Howell ANSIX Type-V lens f/3.5.  The lens has 2 marker rings. The outer ring is to be rotated to match the selected shutter speed, 16, 32, or 64.  The letters B (Bright), H (Hazy), and D (Dull) are displayed on the inner ring, which is then rotated to select the expected lighting condition when the targets will be encountered. A Yellow (Minus Blue) filter is attached, which cuts through haze, darkens the sky, and protects the lens from dirt and oil.  

There are two electrical connectors. A 4-pin barrel type connector for power and actuation is located on its side, and a 2-pin connector is located in front to power a separate heating element (not included).

Included in the kit is an extra 35mm Wollensak 1 inch f 19 Cine-Velostigmat lens marked Naval Research Lab, with focal length from 2 to INF and f-stop 1.6 to 19.  There is also an extra Yellow filter and a metal plate to install on the camera body should the lens be removed.

The camera itself appears to be in good cosmetic condition. All of the mechanical parts appear to operate as intended, however, electrical input is required to test its full functionality, which has not been checked. The original case is included, but the leather strap handle has not survived.  Otherwise, it is in fine condition given its apparent age.