Mamiya RT-11978

History

Mamiya's M42 SLR line began in the mid-1960s with the Mamiya Prismat and 1000 DTL series - multi-pattern metering bodies that were competitively specified against Pentax Spotmatic and Fujica ST series cameras. The MSX 1000 (1974) moved to an electronic vertical metal shutter, replacing the earlier horizontal cloth design, and introduced electronic metering circuitry. The RT-1 followed around 1978 as a further refinement: the electronic shutter platform was retained but aperture-priority automation was added, reflecting the market shift toward auto-exposure that Pentax had accelerated with the ME and MX in 1976.

By 1978 the M42 mount was commercially aging. Pentax had introduced the K-mount in 1975, and most Japanese manufacturers had moved or were moving to proprietary bayonet mounts offering full-aperture metering and automation. Mamiya itself followed suit with the CS-mount ZM Quartz series from 1982. The RT-1 is therefore a transitional camera: technically capable within the M42 system, but produced for only a short period before the entire M42 platform was retired by the industry.

Why It Matters

The RT-1 is the most capable M42-mount camera Mamiya produced, and for users of M42 lenses it represents the practical ceiling of the Mamiya M42 system. Aperture-priority exposure - setting the aperture on the lens and allowing the camera to select shutter speed - was the dominant automation mode of the late 1970s and remains practical for general photography. The electronic shutter's 1/1000s ceiling is sufficient for most subjects, though not competitive with the 1/2000s or 1/4000s available in contemporaries such as the Fujica ST 901 or Pentax LX.

The RT-1's chief appeal today is as a capable, low-cost body for the large installed base of M42 lenses. It supports stop-down metering with any M42 glass, and its aperture-priority mode works correctly with Mamiya's own M42 Sekor lenses that carry the automatic aperture linkage pin.

Lenses & Accessories

The RT-1 accepts all M42 screw-mount lenses. With Mamiya's own M42 Sekor lenses carrying the auto diaphragm pin, full-aperture-priority operation is available. With third-party M42 glass (Takumar, Flektogon, Helios, Jupiter, Industar, Carl Zeiss Jena M42 series), stop-down metering is used. No dedicated winder or motor drive was produced for the RT-1. Standard M42 extension tubes and bellows are compatible for close-focus work.

Notable compatible M42 lens families:

• Mamiya-Sekor M42 series (35/2.8, 50/2.0, 55/1.8, 135/2.8, 200/3.5) - native, full-aperture priority
• Asahi Takumar / Super-Takumar / SMC Takumar series
• Carl Zeiss Jena (Pancolar, Flektogon, Tessar, Sonnar) via Pentacon Five or East German M42
• Helios 44-2 and 44M variants (Soviet M42)

Sample Photographers / Notable Use

• Enthusiast and semi-professional users of the M42 system in the late 1970s, particularly in markets where Mamiya had established distribution.
• Today used as a cost-effective aperture-priority body for M42 legacy glass.

References

• Camera-Wiki: Mamiya RT-1
• Wikipedia: Mamiya