Pentax's budget screw-mount SLR — the S1, all-mechanical eye-level body, screw mount, 1961.
The Pentax S1 of 1961 was a lower-cost member of the screw-mount S-series, offered as a more affordable companion to the S3. It was sold in the US as the H1 under Honeywell branding. It sits within the all-mechanical Pentax line that developed the eye-level SLR before the metered Spotmatic arrived.
This is a 35mm film SLR using the screw lens mount that became the M42 standard, taking Asahi's screw-thread lenses. It has a horizontal cloth focal-plane shutter and a fixed eye-level pentaprism with an instant-return mirror. There is no built-in meter, so exposure is set manually, and the body is fully mechanical, firing without a battery. As the budget model it carried a reduced top shutter-speed marking compared with the S3, though the mechanism was closely related.
The S1 suits collectors, students and photographers who want an inexpensive, simple screw-mount Pentax with a clear finder. It handles directly and dependably, needing a separate meter or experience for exposure. It is a straightforward body for slow, considered shooting and a low-cost way into the M42 system.
As an early-1960s body, checks apply. Inspect the cloth shutter for pinholes and even travel, testing the slow speeds for sticking. There is no meter or battery to consider. Examine the pentaprism and finder for desilvering, haze or fungus. Confirm the film advance and rewind feel smooth. Clean, working screw-mount lenses keep the camera usable.