The Pentax A3/A3000 was designed as a beginner's SLR in the year 1984 it features built-in winder, Auto exposure (With compatible FA lenses and beyond), It has 4 modes; Program (Includes Av with certain lenses), 1/60, and Bulb mode.
The program mode on this camera is very basic and the only manual control for controlling this is on the left side, near the base of the lens mount. This is a push button labelled BACK LIGHT +1.5 when pressed it sets the exposure compensation to +1.5 EV.
This mode sets the shutter speed to 1/60 sec which is the flash sync speed, while this mode is on the light meter is deactivated and the user is allowed to adjust the aperture accordingly.
Bulb mode, aperture is set automatically on compatible lenses.
The camera fetures DX Coding which only allows the +1.5 EV button to alter the auto exposure, however for any other film you can adjust the exposure by using the ISO dial. The camera has an ISO range from 25-16,000.