PETRI PENTA

Name: Petri Penta
Brand: Petri

The Petri Penta, introduced in 1959, was the first single-lens reflex (SLR) camera produced by Kuribayashi Shashin Kōgyō (later known as Petri Camera Company), marking the company’s entry into the competitive 35mm SLR market. It was a technologically ambitious design for its time, featuring a unique instant-return mirror system and one of the earliest implementations of the M42 screw lens mount.

Overview

The Petri Penta was developed during a period of rapid innovation in Japanese camera engineering, as domestic manufacturers sought to challenge German dominance in the SLR segment. Released between 1959 and 1962, the Penta represented a bold departure from Petri’s previous focus on compact rangefinder and viewfinder cameras. It was positioned as a high-end amateur and semi-professional tool, offering advanced mechanical features and compatibility with a wide range of interchangeable lenses via the newly standardized M42 mount. The camera featured a vertically traveling focal-plane shutter and an instant-return mirror—a rare feature at the time—which allowed continuous viewing after exposure, significantly improving usability over contemporary SLRs that darkened the viewfinder until the film was advanced.

Despite its innovative design, the Penta suffered from complex mechanics and limited production volume, contributing to its relatively short production run. It was succeeded by the simplified Petri Penta S and later models that abandoned the instant-return mechanism. Within Petri’s product lineage, the Penta served as a technological flagship, demonstrating the company’s engineering capabilities even if it did not achieve widespread commercial success. Its design reflected the broader trend among Japanese manufacturers to experiment with automation and improved user experience in the late 1950s and early 1960s.

Specifications

Specification	Value
Type	35mm Single-Lens Reflex (SLR)
Film Format	35mm (135 cartridge)
Years Produced	1959–1962
Lens Mount	M42 × 1 screw mount (Praktica thread)
Shutter	Cloth focal-plane shutter, speeds 1 sec to 1/1000 sec + B
Metering	None (uncoupled; later accessories allowed external meter use)
Exposure Modes	Manual only
Viewfinder	Eye-level pentaprism with split-image rangefinder spot (interchangeable focusing screens available)
Dimensions	Approx. 148 × 95 × 55 mm; weight approx. 710 g (body only)

Key Features

Instant-return mirror mechanism: One of the first Japanese SLRs to feature automatic mirror return after exposure, enabling uninterrupted viewing—predating similar systems in Nikkormat and Canon cameras.
M42 screw mount: Adopted the emerging universal thread standard, allowing compatibility with a broad range of lenses from Zeiss, Meyer, Pentacon, and later Japanese makers.
High-speed shutter: Offered 1/1000 sec—the fastest available on any production SLR at its launch—achieving this via a vertically traveling cloth shutter.
Interchangeable focusing screens: Allowed users to swap screens for different shooting needs, such as microprism or grid patterns.
Crank-type film advance: A large, rapid-wind lever with a 180-degree throw, enabling faster frame-to-frame operation than many contemporaries.

Historical Context

The Petri Penta was launched at a pivotal moment in the evolution of 35mm photography. In the late 1950s, SLRs were transitioning from niche technical tools to mainstream photographic instruments, driven by demand for through-the-lens composition and easier macro and telephoto work. Japanese manufacturers like Asahi (Pentax), Nikon, and Topcon were refining their SLR designs, while European brands such as Zeiss Ikon and Ihagee (Exakta) held strong reputations. The Penta entered this competitive arena with several cutting-edge features, most notably its instant-return mirror—a feature not widely adopted until the mid-1960s.

Despite its innovations, the Penta faced stiff competition. The Asahi Pentax AP series, introduced earlier, had already established M42 as a viable standard, and Nikon’s F-mount system (1959) offered superior build and system expandability. The Penta’s complex mirror mechanism proved fragile and expensive to produce, limiting its appeal to a niche audience. It was never widely exported, and distribution remained concentrated in Japan and select European markets. Reviews at the time praised its optical quality and advanced mechanics but noted reliability concerns and high cost relative to rivals.

Collectibility & Value

Today, the Petri Penta is a rare and sought-after collector’s item, particularly among enthusiasts of early Japanese SLR development. Fewer than 10,000 units are estimated to have been produced, and working examples are uncommon due to the complexity of the mirror mechanism and degradation of rubber shutter components over time. In good cosmetic and functional condition, the Penta typically sells for $400–$700 USD at auction or through specialist vintage camera dealers, with fully serviced models commanding higher prices.

Collectors should inspect several key areas when acquiring a Penta: the mirror return mechanism must operate smoothly without sticking; the shutter should fire consistently across all speeds, especially 1/1000 sec; and the film advance crank should engage without slippage. Common issues include seized mirror springs, light seals disintegration, and shutter curtain fraying. Because replacement parts are scarce, cameras in original, unmodified condition are preferred. Original boxes, manuals, and accessories such as lens hoods or body caps can significantly enhance value.

Similar Cameras

Asahi Pentax Spotmatic (1964) – Shared the M42 mount and refined SLR ergonomics, though introduced later with TTL metering.
Topcon RE Super (1963) – A high-end Japanese SLR with interchangeable viewfinders and advanced optics, but without instant-return mirror.
Praktica FX 2 (1964) – East German M42 SLR with robust build, though slower max shutter (1/500 sec) and non-instant return.
Fujica ST 705 (1962) – Fujifilm’s early M42 SLR, simpler mechanics but more reliable production.
Konica F (1960) – Another Japanese pioneer with high-speed shutter (1/2000 sec) and focal-plane design, though with a non-returning mirror.

Repair & Maintenance

The Petri Penta does not require batteries for operation, as it is fully mechanical. However, accurate light metering must be performed using an external meter or modern handheld device. The most frequent maintenance issues involve the shutter and mirror mechanisms. The vertically traveling cloth shutter is prone to uneven tension at high speeds, particularly 1/1000 sec, and may require re-timing or replacement of the rubberized cloth if degraded. The instant-return mirror spring assembly is delicate and often fails due to fatigue; disassembly requires precision tools and familiarity with SLR mirror boxes.

Regular servicing should include cleaning of the pentaprism housing, replacement of deteriorated light seals around the film chamber, and lubrication of the film transport gears. The crank-type advance lever uses a spring-loaded clutch system that can wear over time, leading to incomplete film advance or double-exposure risk. Due to the scarcity of OEM parts, repair technicians often rely on donor cameras or custom fabrication. As such, the Penta is not recommended for novice collectors or those seeking a reliable daily-use vintage SLR, but remains a prized specimen for technical historians and connoisseurs of early Japanese camera innovation.