The Canon FPD-400 is a Digital Focus Servo Demand controller designed for Canon professional video lenses. It provides precise and responsive control over the focus function of compatible Canon lenses, particularly in digital ENG (Electronic News Gathering) and EFP (Electronic Field Production) applications.

Key features of the Canon FPD-400 include:

Focus Control: Enables users to achieve accurate and smooth focus adjustments, crucial for professional video production.

Digital Servo Demand: The servo system ensures precise and responsive control over the focus operation of the connected Canon lens.

Compatibility: Specifically designed to work seamlessly with Canon lenses, ensuring optimal performance and integration with Canon's professional video equipment.

The "CR-10" mentioned alongside the FPD-400 likely refers to a related accessory or controller that complements the functionality of the FPD-400 within Canon's professional video production setup. It could be an additional control unit or an extension to enhance the operational capabilities of the focus servo demand.