Pentax Auto 110 (1978–1985)

A subminiature interchangeable lens SLR camera using 110 film, produced by Asahi Pentax as a compact system with TTL metering and automatic exposure.

Overview

The Pentax Auto 110 is a subminiature single-lens reflex camera designed for 110 film cartridges, introduced in late 1978 by Asahi Pentax. It's recognized as the smallest interchangeable lens SLR ever made with through-the-lens metering. Despite its tiny size—often mistaken for a toy—it offered advanced features for its format, including programmed exposure, TTL metering, and a range of dedicated lenses and accessories. The system was updated in 1983 with the Auto 110 Super, which shared compatibility with the original’s lenses, batteries, and most accessories, though the Winder II was exclusive to the Super model.

Specifications

Shutter speeds	1 sec to 1/750th
Exposure range	EV 3 to 17 at ASA 100
Aperture ranges	f/2.8 to f/13.5
Light meter cell	silicon photo cell
Metering system	Centerweighted
Film speed indexing	Automatically indexes for ASA 400 film; lower setting is ASA 80
Viewfinder magnification	0.75x
Viewfinder coverage	87%
Battery	Two 1.5V silver oxide batteries (type D76/S76, PX76)
Battery life	Estimated 10,000 exposures or one year
Winder	Two AA battery powered winder; single frame advance only, not sequential
Film Format	110 cartridge (13x17mm)
Size	56 x 99 x 32 mm (w/o lens)
Weight	159g (w/o lens)
Original List Price (1979)	$249.00 (w/24mm lens, case, and strap)

Design

The Pentax Auto 110 uses drop-in 110 cartridge loading and features fully automatic exposure. Electronics are turned off by partially depressing the shutter release until resistance is felt—a unique power-saving design often overlooked. The viewfinder is noted for being large and high-contrast for the 110 format, aiding precise focusing in a compact body.

Context

Pentax positioned the Auto 110 as a high-quality system for the 110 film format, aiming to elevate it beyond consumer snapshot use. It was succeeded by the Auto 110 Super in 1983, maintaining full compatibility with the original’s lenses and accessories except for the Winder II. The system included multiple lenses, flashes, and winders, offering SLR capabilities in an unusually small form factor.

Market

The Pentax Auto 110 is regarded as a collectible curiosity, with standard bodies available around $100 and full kits reaching up to $300. Rare variants like the transparent "See Through" dealer model and the "Safari" presentation set command higher interest. Common issues include dead electronics, slipping film advance, and stuck aperture diaphragms. Service manuals are available, aiding repair and maintenance.