The Nikonos III, released in 1975, was the third and final model in the series to be based on the original mechanical "Calypso" design. It is widely considered the peak of the mechanical Nikonos line, offering significant refinements in film handling and framing accuracy over its predecessors.
Key Improvements and Features
Film Transport System: For the first time in the series, a sprocket gear was used for film advance. In previous models, frame spacing was irregular because it relied on the thickness of the film on the take-up spool; the III achieved precise, equal spacing.
Top-Mounted Frame Counter: The frame counter was moved from the bottom of the camera to the top deck for easier visibility while shooting.
Enhanced Viewfinder: It introduced an illuminating window-type bright frame. This provided a clearer field of view and included dedicated frame lines for both 35mm and 80mm lenses.
Mechanical Reliability: Like the I and II, it is fully mechanical and requires no batteries. This makes it highly durable and capable of operating even if the seals fail (after a fresh-water rinse and dry).
Simplified Loading: The take-up spool was improved with two grooves for easier film attachment, and the hinged pressure plate was redesigned to open downward for better access.