In the camera disclosed, depending upon whether the shutter preference or aperture preference mode is selected, a computer establishes a computed value on the basis of a preset value and other ambient conditions. A number of separate comparators compare the respective values to a single reference wave form and turn off respective gates when the analog voltages achieve predetermined relationships to the reference wave form. The gates passed pulses from a common source from the beginning of the reference wave form until the respective gates are shut off. The values are thus digitized and displayed within the camera.