15.875mm stud (5/8″) for mounting lights to C-stands; supports up to 25kg vertically and allows 360° rotation.
Technical Details
The Junior Pin measures exactly 15.875mm (5/8") in diameter with a typical length of 50-80mm. The tolerance is ±0.05mm for a precise fit without play. Standard versions feature a circumferential groove for O-ring seals and a flattened side for anti-rotation. The maximum load capacity is 25kg vertically and 15kg horizontally, depending on the receiver used. Modern variants utilize anodized aluminum (Series 7075-T6) or hardened steel with corrosion protection.
History & Development
Mole-Richardson developed the Junior Pin system in 1947 in response to the growing mobility of film production outside of studio stages. The system replaced the previously common screw connections and reduced setup times by approximately 60%. In 1952, the American Standards Association (ASA) standardized the dimensions, creating compatibility between different manufacturers. From the 1980s onwards, the system also established itself in the European film industry as the standard for HMI lights in the 575W-2500W class.
Practical Application in Film
Junior Pins are found on Fresnel lights such as the Arri 650 Plus or HMI fixtures like the K5600 Joker-Bug 800W. Cinematographers use them for key light positions where quick adjustments of the light direction are required. In "Blade Runner 2049" (2017), Junior Pin mountings enabled the rapid repositioning of HMI lights for Villeneuve's characteristic backlight setups. The system allows for 360° rotation and approximately 200° tilt angle, limited by the mechanical construction of the receiver.
Comparison & Alternatives
Unlike the smaller Baby Pin (1/2"), the Junior Pin carries heavier lights, while the Senior Pin (1 1/8") remains reserved for studio lights from 5kW upwards. Modern alternatives such as the Manfrotto 16mm spigot system offer identical functionality with optimized materials. LED panels are increasingly using the lighter Baby Pin system, while classic Tungsten and HMI lights remain standard with the Junior. Quick-release systems like the Matthews Mafer Clamp replace Junior Pins for temporary mounting on irregular surfaces.