Petri PX5

The Petri PX5 is a particularly compact 35mm AE camera, introduced in the early 1980s. It impresses with its user-friendly handling, an integrated electronic flash, and fixed optics. This model is structurally identical to the Cosina CX5 and also rolled off the production line at the Japanese company Cosina.

Designed as a point-and-shoot camera with some manual adjustment options, the Petri PX5 was aimed at amateur photographers who needed a camera for carefree snapshots.

There was also a functionally reduced version known as the Petri PX5F and Cosina CX5F. These two variants offered, for example, fewer ISO sensitivity options and featured a fixed focus setting. All four versions (PX5, CX5, PX5F, CX5F) were manufactured by Cosina.

Lens of the Japanese camera

The Petri PX5 is equipped with a fixed COSINON 1:3.8 lens. The focal length is 33 mm, which corresponds to a moderate wide-angle and is well suited for everyday photography, landscape panoramas, and snapshots.

The optical design comprises four lenses in three elements. Since the optics are permanently integrated, replacing the lens is impossible.

Focus is adjusted manually via a zone-focusing system. This is done using a small lever (focus lever) on the front of the lens. Three markings (focus symbols) serve as orientation: a person symbol for portrait shots at close range (approx. 1.1 m), a circle symbol (often interpreted as a group symbol) for general snapshots in the main focus area (approx. 2.7 m), and a mountain symbol for landscape subjects (infinity). Focusing at 2.7 m creates an extended depth of field (pan-focus effect), allowing most objects to be sharply reproduced in common snapshot scenarios.

There is no integrated filter thread. A special feature is the built-in lens cover – a rotating cover (“blink” lens cover). When closed, this shields the lens and simultaneously locks the shutter release mechanism to prevent accidental exposures.

Exposure Settings

Exposure on the Petri PX5 is controlled automatically by a programmed automatic exposure (AE) system. The system measures subject brightness using a photodiode that acts as a light sensor. Based on this measurement and the set film speed, the camera automatically determines an appropriate combination of shutter speed and aperture.

The automatic exposure metering range is from EV 8.6 to EV 17 (based on ISO 100). The user can manually select the film speed using a slider on the front of the camera.

Films with ISO speeds of 64, 100, 200, and 400 are compatible. For films with different speeds, the closest setting should be used. Direct manual selection of aperture or shutter speed is not possible.

A red warning LED is located in the viewfinder window. It flashes when the lighting conditions are too low for handheld shooting (corresponding to an exposure time of approximately 1/30 of a second or more). This LED also serves as a battery level indicator.

Flash System

The Petri PX5 features a built-in automatic electronic flash. It is designed as a pop-up flash and extends from its resting position by pressing a slider (Flash on button) on the front of the camera.

When the flash is popped up, charging begins automatically. A flash-ready lamp next to the viewfinder illuminates as soon as the flash is fully charged and ready for use.

The flash’s guide number is 12 (for ISO 100, given in meters). The flash recharge time, i.e., the time until the flash is ready for use again after a trigger, is approximately 7 seconds. The actual flash duration is very short at approximately 1/1000 of a second.

The effective flash range extends from 0.9 meters to 3 meters when using ISO 100 film.

The red warning LED in the viewfinder alerts the photographer when ambient light is too dark and using the flash would be advisable. When the flash is no longer needed, it should be manually pushed back into the housing until it clicks into place to conserve battery life.

Additional Features

Beyond its core functions, the Petri PX5 boasts additional features.

The viewfinder is a bright-frame type and offers 0.5x magnification. It includes markings for parallax compensation. These help determine the correct composition for close-up shots (focus at 1.1 m), as the view through the viewfinder differs slightly from the lens’s angle of view.

The aforementioned red LED in the viewfinder serves both as an underexposure warning and to check the battery level.

The film advance is manual using a thumbwheel on the back of the camera. A full 360-degree rotation advances the film by one frame. An internal mechanism prevents accidental double exposures.

The film counter counts forward and automatically returns to “S” (start) when the back is opened. The numbers 12, 20, 24, and 36 are highlighted in orange to indicate the end of standard film runs.

The film rewind is also manual. After pressing the film rewind button on the bottom of the camera, the film is rewinded into the cartridge using the fold-out film wind crank.

A strap hole for attaching a wrist strap is also provided. A self-timer is not mentioned in the technical specifications and is therefore missing. There is also no tripod thread.

Dimensions and Weight

The Petri PX5 is an extremely compact camera. Its dimensions are 117 mm wide, 67.5 mm high, and 42 mm deep. The camera weighs 230 grams without batteries. With batteries, the weight increases slightly. Thanks to its small size and low weight, it is a very portable camera for on-the-go use.

Camera Power Supply

The Petri PX5 is powered by two 1.5V AAA alkaline batteries (eBay / Amazon*).

The batteries are housed in a compartment on the bottom of the camera, which is closed with a sliding cover (battery compartment cover). The correct orientation of the (+) and (-) poles is indicated in the battery compartment and must be observed when inserting them.

The camera is equipped with a battery check function that uses the red LED in the viewfinder. To test, open the lens cap, place your finger on the light sensor (photosensor eye), and lightly press the shutter button. If the red LED in the viewfinder flashes, the battery power is still sufficient. If the LED doesn’t light up, the batteries need to be replaced or their correct seating checked. When the lens cap is closed, the shutter release is mechanically locked, preventing power consumption from accidental activation.

Film Recommendations for the Petri PX5

The Petri PX5 is designed for use with 35mm film (24x36mm format). The film speed must be set manually using the ASA/ISO selector switch, as the camera does not have DX code scanning. Films with ASA/ISO 64, 100, 200, and 400 can be used.

The choice of film speed depends on the intended use and the prevailing lighting conditions:

• ISO 100 or 200: These are good all-round speeds for outdoor photography in daylight, such as landscapes or general snapshots in good weather. ISO 200 offers a little more flexibility in cloudy skies or in shadows.
• ISO 400: This film is better suited for low-light situations, such as indoors (especially with flash), at dusk, or for fast-moving subjects (sports), as it allows for shorter exposure times.
• ISO 64: This low-speed film potentially offers the finest grain and the highest detail, but requires very bright lighting conditions, such as sunny days at the seaside or in the snow.

Various manufacturers continue to offer suitable film materials. For color images, the Kodak Gold 200* is suitable. An option for black and white photography is the Ilford Delta 400*. Other manufacturers include Fujifilm, Foma, and Lomography.

The exposure counter indicates the number of shots taken and marks the typical roll lengths of 12, 20, 24, or 36 images. Both color negative film (for paper prints) and black-and-white film can be used. Slide film can also be used, but it places greater demands on the camera’s exposure precision.

Quick Operation Guide

Since the Petri PX5 is identical to the Cosina CX5, it is operated using these instructions:

1. Inserting Batteries: Open the battery compartment on the bottom and insert two AAA alkaline batteries, observing the correct polarity.
2. Loading Film: Open the camera back using the back cover open knob. Insert the film cartridge into the film chamber. Pull the film tab over the film guide rail and insert it into a slot on the film take-up spool.
3. Initializing Film Advance: Close the back cover. Turn the film advance wheel 360°, press the shutter button, and repeat the process until the film counter reaches “1.”
4. Adjust the film speed: Set the ASA/ISO value of the film being used using the film speed selector.
5. Prepare the camera for shooting: Turn the lens cover sideways to expose the lens and unlock the shutter release.
6. Select the focus: Use the focusing lever to select the appropriate distance (1.1m, 2.7m, or ∞). 2.7m is suitable for most snapshots.
7. Compose the image: Look through the viewfinder and select the desired section. When taking close-ups, pay attention to the parallax markings.
8. Checking exposure / using the flash: Lightly press the shutter button. If the red LED in the viewfinder flashes, there is insufficient light. Slide the flash on button to pop up the flash. Wait until the flash ready lamp lights up.
9. Trigger: Press the shutter button all the way down to take the photo.
10. Advance film: Turn the film advance dial one full turn until it stops for the next shot.
11. Rewind film: When the film is full (advance dial is blocked), press the film rewind button on the bottom. Extend the film wind crank and turn it clockwise until the film is completely rewound (the crank will turn more easily).
12. Remove the film: Open the back cover and remove the film cartridge.