Pentax's screw-mount SLR — the H3, the S3 sold as Honeywell in the US, screw mount, 1961.
The Pentax H3 of 1961 was the US Honeywell-branded version of the S3, sold under the H prefix in that market. Mechanically it is the S3, with its fully automatic-diaphragm lens operation. It belongs to the all-mechanical screw-mount Pentax line that ran up to the Spotmatic.
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 by hand, and the body is fully mechanical, firing without a battery. It used automatic-diaphragm lenses that stayed open for viewing and closed down at exposure.
The H3 suits collectors, students and photographers who want a simple, robust screw-mount Pentax with smoother lens handling than the earliest models. It handles like the S3 and needs a separate meter or experience for exposure. It is a dependable body for considered work, and the Honeywell branding adds collector interest.
As an early-1960s body, condition is key. Check the cloth shutter for pinholes and even travel, testing the slow speeds for stickiness. There is no meter or battery here. Inspect the pentaprism and finder for desilvering, haze or fungus. Test the advance and rewind for smooth movement. Clean, working screw-mount lenses determine practical usability.