PETRI FLEX V

The Petri Flex V was introduced around 1960 and stayed in production until approximately 1963. Exact production dates are not well-documented, but 1961-1964 is an overspecification. It was a transitional model in Petri's early push into the SLR market. It combined improved optics with a compact design aimed at amateurs who wanted better image quality without the complexity of professional systems.

Overview

Introduced in 1961, the Petri Flex V was part of a short-lived but ambitious line of SLRs that Petri developed in the early 1960s. Japanese manufacturers were rapidly expanding into the SLR segment then, which was dominated by brands like Asahi (Pentax) and Nikon. The Flex V succeeded earlier models such as the Flex IV and was a modest upgrade, distinguished mainly by its better lens optics. Many contemporary SLRs took interchangeable lenses on proprietary bayonet mounts. The Flex V did not. It used a fixed Petri Anastigmat 50mm f/2.8 lens, now with a five-element formula instead of the earlier four-element design. The five-element layout gave better contrast, reduced aberrations and improved sharpness, particularly at wider apertures.

Petri marketed the camera to advanced amateurs who valued optical quality and mechanical simplicity. It has a focal-plane shutter with speeds from 1 second to 1/1000, a vertically traveling cloth curtain, and a built-in selenium light meter coupled to the shutter speed dial. That was a fairly advanced feature for a fixed-lens SLR at the time. The meter needs no battery. It runs on ambient light alone and shows its exposure recommendation with a needle visible in the viewfinder. The Flex V used a standard M42 screw-thread mount for accessories and filters, though the lens itself was not interchangeable. The body is compact magnesium alloy, with a top-mounted rewind lever.

Specifications

Specification	Value
Type	Single-Lens Reflex (SLR)
Film Format	35mm (135 cartridge)
Years Produced	1961–1964
Lens Mount	Fixed lens; filter thread: M42×1 (screw)
Lens	Petri Anastigmat 50mm f/2.8, 4 elements in 3 groups
Aperture Range	f/2.8 to f/16
Shutter	Focal-plane, cloth curtain, vertical travel
Shutter Speeds	1s – 1/1000s + B (Bulb), X & M flash sync at 1/60s
Metering	Built-in selenium cell exposure meter (center-weighted)
Exposure Modes	Manual only; meter aids shutter/aperture selection
Viewfinder	Fixed pentaprism, eye-level, with central split-image rangefinder and microprism collar
Focusing	Manual via helicoid lens barrel, 0.45m minimum focus
Flash Sync	PC terminal, X/M switch for bulb or electronic flash
Frame Size	24 × 36mm
Frame Counter	Manual reset (reset by opening back)
Film Advance	Single-stroke lever (90° throw), stroke cocks shutter and advances film
Self-Timer	Mechanical self-timer with lever on front
Dimensions	Approx. 138mm (W) × 84mm (H) × 47mm (D)
Weight	Approx. 580g (with lens, no battery)

Key Features

Five-element Petri Anastigmat 50mm f/2.8 lens: Improved optical performance over earlier four-element versions, offering superior sharpness and reduced chromatic aberration.
Integrated selenium light meter: No battery required; needle indicator in viewfinder aligns with shutter speed for correct exposure.
Vertical-travel focal-plane shutter: Enables high-speed flash sync (1/60s) and reliable operation up to 1/1000s.
Split-image focusing screen: Enhanced manual focusing precision with central split-image prism surrounded by microprism collar.
Compact magnesium alloy body: Lightweight yet durable construction typical of Petri’s mid-tier models.

Historical Context

The Petri Flex V appeared when SLRs were moving from niche professional tools to accessible consumer products. Petri was traditionally known for rangefinders and compact cameras, and it entered the SLR market cautiously. The Flex series began with the Flex in 1958. There is no official 'Flex I' designation - models were typically called Flex, Flex II, Flex V, etc., without consistent Roman numeral sequencing. The Flex V, released in 1961, was among the last in this line before Petri shifted to more modular designs. Its fixed lens limited its appeal next to interchangeable systems like the Pentax Spotmatic or Nikkorex F. It was a cost-effective alternative for photographers who put lens quality ahead of system flexibility.

Competition was intensifying. Yashica, Fujica and Minolta were introducing SLRs with through-the-lens metering and bayonet mounts. Petri's selenium meters degraded over time, and its lenses were not interchangeable, which put the Flex V at a disadvantage. Despite its technical merits, the model had limited market penetration outside Japan and parts of Southeast Asia. Production ceased by 1964 as Petri redirected resources toward more competitive designs, such as the Petri Penta series. The Flex V remains a footnote in SLR evolution.

Collectibility & Value

The Petri Flex V is moderately rare today. Surviving units often turn up in mixed condition, since selenium meters deteriorate with age. Examples with working meters are uncommon. Most collectors accept a dead meter as long as the shutter and film advance work correctly. In the current vintage camera market (2023-2024), prices range from $80 to $180 USD depending on condition, and fully operational units command premiums. Buyers are mainly Petri enthusiasts, SLR historians and collectors of obscure Japanese optics.

When buying a Flex V, inspect the shutter at all speeds, particularly 1/500 and 1/1000, which may stick because of aged lubricants. The selenium meter cell, exposed on the top plate, is prone to darkening and delamination. It cannot be easily repaired, but a dead cell does not affect mechanical function. Lens fungus and haze are rare but possible, and the five-element Anastigmat is generally well-preserved if stored properly. The self-timer can bind if not exercised. The film advance lever may have play if the internal linkage is worn. Overall, the Flex V is a stable platform for modern film, provided basic maintenance is done.

Similar Cameras

Yashica Pentamatic (1959–1962): Fixed-lens SLR with 50mm f/1.8, M42 body, selenium meter.
Fujica Six SLR (1963): Though a 6×6 TLR-style SLR, shared Petri’s focus on premium fixed optics.
Minolta SR-2 (1958): Interchangeable lens SLR with advanced viewfinder and Copal shutter.
Konica Auto-Reflex (1965): Later fixed-lens SLR with auto-exposure, showing the direction Petri might have taken.
Pentax Spotmatic (1964): Represented the new standard in SLRs with TTL metering and M42 interchangeability.

Repair & Maintenance

The Petri Flex V needs no batteries. Its selenium meter works passively but cannot be replaced if it degrades. Common maintenance issues include stiff or inaccurate shutter speeds from dried lubricants, especially in cameras stored for decades. For regular use, a full CLA (clean, lubricate, adjust) by a technician experienced with vintage Japanese SLRs is recommended. The focal-plane shutter curtains are delicate and should not be left tensioned. The film advance mechanism is sturdy but may need the sprocket and pressure plate cleaned. Check the lens helicoid for smooth focusing, and clean the aperture blades to prevent sticking. Storage in a dry, temperature-stable place helps. Parts are scarce, so repairing major components (e.g., shutter replacement) may require donor cameras.