Cosina PM-1

The Cosina PM-1 is a 35mm film single-lens reflex (SLR) camera, characterized by its manual operation and robust design. It is one of a series of camera systems aimed at offering solid photographic performance at an affordable price.

Lens

The Cosina PM-1 often comes standard with a Cosina Auto SQ 50mm f/2 lens.

This lens has a fixed focal length of 50mm, which corresponds to a natural angle of view of approximately 46 degrees and is well suited for general photography. The maximum aperture of f/2 enables shooting even in less favorable lighting conditions and offers creative possibilities through a shallow depth of field. The lens features a standard 49mm filter thread for attaching filters or other accessories. The minimum focusing distance of this standard lens is 0.5 meters.

The lens mount is the widely used Pentax K bayonet, a robust bayonet mount. This means the camera is compatible with a wide range of lenses that feature this mount, including wide-angle, telephoto, and macro lenses from various manufacturers.

Focusing is achieved manually by turning the focusing ring on the lens. A central microprism array in the viewfinder assists in focusing. This array displays a clear image when correctly focused, while shimmering or refracting when out of focus. Alternatively, the entire focusing screen can be used for focusing.

The 50 mm lens features a distance scale and a depth-of-field scale, allowing you to estimate the depth of field at a specific aperture and distance. A separate infrared index mark is provided for infrared photography to compensate for focus shift in this wavelength range.

Attaching and removing lenses is done by pressing the lens release lever on the camera body and rotating the lens. Proper lens locking is essential for accurate exposure metering and proper function; a small button (finger button) can help ensure the lens is correctly attached, even in the dark.

Exposure Settings

The Cosina PM-1 is equipped with a TTL (through-the-lens) exposure metering system, which measures the brightness of the light entering the lens.

Metering is performed at open aperture (open aperture metering) and uses center-weighted metering. This means that the central area of ​​the image is given greater weight, but ambient light is also taken into account.

The exposure is displayed via a match needle system in the viewfinder. A needle moves along a scale with ‘+’ (overexposure) and ‘-‘ (underexposure) markings. The user sets the aperture and/or shutter speed so that the needle is positioned midway between the markings, indicating correct exposure.

The exposure meter is activated by gently pulling the film advance lever from its retracted position to a standby position (approx. 30 degrees). When the lever is folded back against the body, the exposure meter switches off to conserve battery power, and the shutter release is blocked.

The shutter is a mechanically controlled, vertically traveling metal-blade focal plane shutter. It offers a wide range of manually selectable shutter speeds: from 1 second to 1/1000 of a second, as well as the ‘B’ (Bulb) setting for long exposures, in which the shutter remains open as long as the shutter release is pressed.

Shutter speeds are selected using a dial on the top of the camera. The individual steps click into place precisely; intermediate positions should be avoided, as they can lead to incorrect exposures. Each step corresponds to doubling or halving the exposure time compared to the adjacent step. The exposure meter does not function in the ‘B’ setting.

The aperture is set directly on the lens’s aperture ring. The available aperture values ​​depend on the lens used (f/2 to f/16 for a standard lens). Smaller aperture numbers (e.g., f/2) mean a larger opening and more light, while larger aperture numbers (e.g., f/16) result in a smaller opening, less light, and a greater depth of field.

Correct exposure is achieved by the combination of the selected shutter speed and aperture, using the needle indicator in the viewfinder as a guide. For shutter speeds below 1/30 second, the use of a tripod is recommended to avoid camera shake.

Flash System

The Cosina PM-1 has basic functions for flash photography. A standardized accessory shoe with a center contact (hot shoe) is located on top of the prism housing. This allows the direct attachment of wireless flash units triggered via the center contact.

The camera synchronizes with electronic flash units at shutter speeds of 1/125 second or slower. Shutter speeds faster than 1/125 second result in partial shadowing of the image by the shutter curtain and are therefore not suitable for flash photography.

Exposure control for flash photography is usually done manually or via the automatic functions of the flash unit used, as the camera itself does not have TTL flash metering.

Additional Features

In addition to its core functions, the Cosina PM-1 offers several useful additional features.

A mechanical self-timer is integrated. It is activated by turning a lever on the front of the camera fully counterclockwise. After the shutter is released, there is a delay of approximately 10 seconds before the shutter is released. This feature is useful for self-portraits or for triggering the camera on a tripod during long exposures without shaking. Once activated, the self-timer cannot be stopped.

The camera is equipped with a standard tripod thread on the bottom (presumably 1/4 inch).

The viewfinder provides a good overview of the subject with a frame coverage of 93% of the actual image area (vertical and horizontal) and a magnification of 0.86x when using the standard 50mm lens.

Another feature is the instant-return mirror, which immediately returns to the viewing position after the shot, thus interrupting the viewfinder image only for the duration of the exposure.

On the back of the camera is a film reminder into which the flap of the film pack can be inserted to remember the film type and film speed.

The film is advanced manually via a quick-release lever with a stroke of 135 degrees and a 30-degree standby position. The frame counter automatically counts from ‘S’ (start) to 0 to the maximum number of frames and automatically resets to ‘S’ when the camera back is opened.

Dimensions and Weight

The Cosina PM-1 is a relatively compact SLR camera. The dimensions of the camera body (without lens) are 133 mm wide, 85 mm high, and 48 mm deep. The body weight alone is 450 grams. With a standard lens attached, the depth and weight increase accordingly.

Power Supply

The power supply of the Cosina PM-1 is used exclusively to operate the built-in light meter. All other camera functions, including the shutter sequence, are purely mechanical and function without a battery.

The camera requires a single 1.35 volt H-C mercury battery (e.g., type PX675). Since mercury batteries are no longer manufactured, alternative solutions such as zinc-air batteries (e.g., WeinCell MRB675), hearing aid batteries with adapters, or special voltage adapters must be used to ensure the correct voltage for accurate exposure measurement.

The battery compartment is located on the bottom of the camera and is opened by turning it counterclockwise with a coin. When inserting the battery, it is important to observe the correct polarity (“+” and “-” markings), as incorrectly inserted batteries will render the light meter inoperable. The lifespan of a battery under normal use is approximately one year.

It is recommended to remove the battery when the camera is not in use for an extended period to prevent leakage and to keep the contacts clean.

Film Recommendations

The Cosina PM-1 uses standard 35mm film in 24x36mm format. The camera has a manual film speed setting in the range of ASA 25 to ASA 1600 (ASA corresponds to today’s ISO value). The setting is made by lifting and turning the ring around the rewind crank until the desired ASA value is displayed in the window. The camera does not have automatic DX code recognition; the film speed must always be set manually.

The choice of film depends on the subject and the lighting conditions. Films with low speeds (ISO 25-100) offer the finest grain and highest sharpness and are well suited for shots in bright daylight, such as landscape or architectural photography.

Medium-speed films (ISO 200-400) are versatile and offer a good compromise between grain and light sensitivity, suitable for general photography, portraits, or overcast conditions.

High-speed films (ISO 800-1600) are used in low-light conditions, indoors without flash, or for sports and action photography where fast shutter speeds are required. However, they exhibit more visible grain.

For color photography, there is the Kodak Ultramax 400*. One option for obtaining black and white images is the Ilford Delta 100*.

The camera can be used with color negative film (for prints), color slide film (for projection or scanning), and black and white film. A standard roll of film typically provides 24 or 36 exposures.

Quick Operation Guide

Basic operation of the Cosina PM-1 includes the following steps:

1. Inserting the Battery: Open the battery compartment on the bottom with a coin and insert a suitable 1.35V battery (or replacement type) with the correct polarity.
2. Loading the Film: Pull the rewind crank up to open the back. Insert the 35mm film cartridge into the film chamber, pull the film leader over the film guide, and insert it into the slot on the take-up spool. Ensure the perforation engages the teeth of the advance wheel. Close the back.
3. Advancing the Film: Operate the film advance lever and press the shutter release. Repeat this (usually twice) until the frame counter reaches ‘1’. Slightly tighten the film by gently turning the rewind crank until you feel resistance. The rewind crank should turn as the film is advanced.
4. Set film speed: Set the ASA/ISO value of the loaded film using the dial below the rewind crank.
5. Activate the exposure meter: Pull the film advance lever out slightly to the ready position.
6. Set exposure: Select a shutter speed using the dial on the top panel. Look through the viewfinder and turn the aperture ring on the lens until the needle in the viewfinder is centered between the ‘+’ and ‘-‘ positions.
7. Focus: Look through the viewfinder and turn the focus ring on the lens until the subject appears sharp in the central microprism field or on the focusing screen.
8. Release the shutter: Compose the image and gently press the shutter button.
9. Advance the film: Fully pull the film advance lever to advance to the next frame.
10. Rewind the film: When the film is full (or you want to remove it first), press the film release button on the bottom of the camera. Extend the rewind crank and turn it clockwise until you feel less resistance. Open the back cover and remove the cartridge.
11. Deactivate the light meter: Fold the film advance lever back completely onto the camera body.