Pentax's auto screw-mount SLR — the ES, aperture-priority electronic auto, M42 mount, 1972.
The Pentax ES of 1972 was the international version of the Electro Spotmatic, bringing aperture-priority automatic exposure to the screw-mount Pentax range. It was among the earlier SLRs to offer electronically-timed auto exposure. It sat as an advanced M42 body alongside the manual Spotmatics near the end of the screw-mount era.
This is a 35mm film SLR using the M42 screw lens mount, taking universal M42 lenses, with open-aperture metering on the correct SMC Takumar lenses. It has an electronically-timed focal-plane shutter giving stepless automatic speeds in aperture-priority mode plus a set of manual speeds, and a fixed eye-level pentaprism with an instant-return mirror. Automatic and slow speeds are electronically controlled and require a battery; without power only the mechanical speeds remain. Metering is TTL.
The ES suits photographers who want automatic exposure within the M42 system for travel, documentary and portrait work. It handles like a Spotmatic while adding aperture-priority convenience for faster shooting. It pairs naturally with SMC Takumar lenses and stays compatible with the wider M42 pool, making it a flexible late screw-mount body.
As an early-1970s electronic body, checks matter. Inspect and expect to replace perished foam light seals and mirror-damper foam. Test the electronically-timed shutter across auto and manual for even, accurate speeds, as ageing electronics can drift. The meter and auto system need a working battery, and the design assumed a 1.35V mercury cell, so a modern replacement may affect accuracy. Check the pentaprism for desilvering or foam haze, and test the advance and rewind. With a dead battery only the mechanical speeds work.