The Konica Auto-Reflex P is a stripped-down version of the Auto-Reflex. Different from the Auto-Reflex, it has no built-in light meter and hence no possibility for automatic AE exposure control.
In the late 60's and early 70's, full-featured SLR cameras were still very expensive, valuable devices. On the other hand, compact cameras almost exclusively had fixed lenses with fixed focal lengths, that did not provide the versatility of today's compact cameras with zoom lenses. To close the gap, many manufacturers simply offered stripped-down versions of their SLR camera bodies as beginner's models and cheaper alternative. So did Konica. The simplest way to make the cameras cheaper was to leave out features that were not absolutely necessary, but costly.
In Germany, the Auto-Reflex P was distributed by Foto-Quelle under their own Revue brand. These specimen carry the designation Revue on the prism housing and SP on the front below the rewind crank. The lettering is also different. The frame size switch is marked 18x24 and 24x36 instead of Half and Full.
The Revue version came with a Hexanon 52 mm / 1:1.8 standard lens designated Hexanon only (without Konishiroku or Konica). This lens had only metric distance scales, none in feet. As the Revue SP has no light meter and thus no automatic AE exposure is possible, on the standard lenses sold with these cameras the normal EE marking is missing on the aperture ring. The aperture ring has a setting for AE exposure, so the lens can also be used in AE mode on respective bodies, but it is only marked with a yellow spot.
In Japan, the Auto-Reflex P was marketed as Konica Autorex P.
The Auto-Reflex P already has the new AR bayonet – not yet in its final variation, though. Because the Auto-Reflex P does not have a light meter, it is not necessary to couple the widest aperture of the mounted lens with the camera body. All later Konica bodies have TTL metering, therefore the bayonet was supplemented with a respective coupling around 1968, with the introduction of the Autoreflex T. Later lenses already providing this coupling mechanism can be used without problems on the Auto-Reflex P. Early lenses made for the Auto-Reflex or Auto-Reflex P, which do not have the coupling mechanism, can only be used on later bodies in automatic mode after a respective upgrade, otherwise the meter will not give correct values. Further informations on this topic you find in the section about the AR bayonet on the lens page.
The Auto-Reflex P has a very special feature: the image size can be changed anytime between normal 24 x 36 mm and half size 24 x 18 mm with the flick of a switch – even mid-roll. The smaller size is accomplished by two metal sheets being brought before the film plane, the transport travel is adjusted accordingly. The film counter travels only every second image when the camera is set to half size. The boundaries of half size images are indicated in the viewfinder by two vertical lines. With half size, up to 72 exposures can be made on a standard 36 exposure 35 mm film, but due to the smaller negative size, the possible maximum size of prints is more limited. The half format images have portrait orientation, for landscape orientation the camera has to be tilted by 90°. However, you should avoid changing the image size mid-roll if you do not want to upset your photo dealer – such films with different image sizes, changing mid-roll, cannot be dealt with properly by automatic enlarging equipment.
Konica even had a lens specifically designed for the half format, the Hexanon Zoom Lens Size 24x18 47-100 mm / 1:3,5. In half format, this lens covers a range from light to medium telephoto, image angle is roughly comparable to a 65-135 mm lens with full-size 24x36 mm image format. There are some limitations for use with full-sized 24x36 mm, because the image circle is too small and the light fall-off in the corners is too strong for proper exposure at some focal lengths.
Like all its successors from the big Autoreflex series, the Auto-Reflex P is extremely sturdily built and takes abuse well. The Copal metal focal plane shutter works reliably even under extremely cold conditions and after a very long time of use.
As everyday camera, I would not recommend the Auto-Reflex P, however – simply because it has no light meter. Additionally, from today's point of view a hot shoe for flash photography is missing, the flash operation via PC synch cable ist quite cumbersome for snapshooting – although for demanding exposures the fitting of the flash on top of the camera is usually not the best position anyway.
Beside the half format capability, the Auto-Reflex P provides a depth-of-field preview lever, a bright viewfinder, a film speed reminder dial on the back door, and a mirror lock-up function (with the self-timer).
On the Auto-Reflex, the prism housing has a window to provide more light for the light meter's scale in the finder. To provide space for the meter's needle instrument, the rewind crank is placed on the very edge of the body and is moving the film cartridge spindle by gears. Both is missing on the meterless Auto-Reflex P, the rewind crank is placed directly on the spindle.
Like all the successing big Autoreflex cameras, the Auto-Reflex P is quite big and – especially by today's standards – quite heavy. The Copal metal focal plane shutter is noisy, the sound can be disturbing on some occasions.
As the Auto-Reflex P is purely mechanical and meterless, it does not need batteries.
An accessory light meter is available for the Auto-Reflex P, the Konica Light Meter III. This cadmium sulfide (CdS) light meter is attached to the shutter speed dial and is coupled with the chosen shutter speed of the Auto-Reflex P - when the shutter speed is changed, the scale in the light meter moves accordingly. After reading the correct f-stop value from the meter, it has to be set manually on the aperture ring of the lens. The Konica Light Meter III requires one PX625 mercury cell for power. It can be set to film speeds between ISO 12/12° and ISO 3200/36°.
A detailed overview over technical data and features you'll find here.