The Keystone 750 Rapid Shot camera was designed and manufactured by Berkey Keystone International in Antwerp Belgium and also here in the USA circa 1970s. It was made to use three types of Polaroid pack film, 108, 107 and 88. It has automatic flash control with an electric eye sensor that only uses flash when needed and also an on/off switch in the front face. Flash is provided by a flash bar and the camera red warning light on the back of the camera will light after each fifth shot telling you to rotate or replace the flash bar. The shutter has to be manually set but is electronic at the same time and has speeds of 10 seconds to 1/500 of a second. The flash, shutter, and the rest of the electronics need four AAA batteries to function. The 750 has an f/8.8 40mm color corrected three element glass lens and you turn the lens escutcheon to the footage you think the subject is from the camera. The lens focus markings are 3.5, 4, 5, 6, 8, 10, 15, 30, and infinity. Like the Polaroids, the 750 uses the lighten/darken exposure control knob and it’s located on the front faceplate. The camera provides a timer on the side to know when to pull the picture from the negative and stop the developing. After you take a picture you pull the white tab and the yellow tab, set the timer for color or black & white. The timer will buzz until the picture has developed for the set time. Once the timer has stopped you peel off the picture with the yellow tab. The timing all depends on temperature and the film packet instructions should be followed. The instruction book for the 750 walks you through the removal and cleaning of the spreader bar assembly that was made quite easy by Berkey keystone.