The Blackmagic Design URSA Mini B4 Mount is an interchangeable lens mount accessory that allows URSA Mini Pro and URSA Broadcast camera bodies to utilize professional broadcast lenses with a B4 mount. This specialized component is engineered to bridge the gap between the camera's super 35mm sensor and the optical characteristics of broadcast zoom lenses, which are traditionally designed for smaller 2/3-inch sensors. The mount itself incorporates an optical element that corrects for the difference in sensor size and focal length, ensuring that B4 lenses provide full sensor coverage and deliver their intended field of view and optical performance on the larger URSA sensor. This enables cinematographers and broadcasters to leverage the extensive range of high-quality, servo-controlled broadcast zooms favored in live production, sports, and studio environments, which offer smooth operation, long focal ranges, and integrated control capabilities.

The installation of the B4 mount transforms the camera into a powerful tool for electronic field production (EFP) and live broadcasting. It maintains full electronic communication between the camera and lenses that support it, allowing for control of zoom, focus, and iris either manually on the lens or remotely via the camera's control interfaces. This integration is critical for multi-camera setups where a technical director needs to make consistent adjustments to all cameras from a central control panel. The mount is constructed from durable materials to withstand the rigors of professional use and is designed for secure, precise attachment to the camera body, ensuring optimal lens alignment and stability, which is paramount for maintaining image sharpness, especially when using long telephoto lenses.

By offering a native B4 mounting solution, Blackmagic Design significantly expands the versatility of the URSA Mini platform. Users can now choose between cinematic EF or PL mount lenses for film-style productions and quickly switch to the B4 mount to equip the camera with a broadcast zoom for live events or news gathering. This flexibility makes the URSA Mini an exceptionally adaptable camera system, capable of serving dual roles within a production company or broadcaster's inventory. For professionals who require the image quality and dynamic range of a super 35mm sensor but depend on the operational ergonomics and lens characteristics of traditional broadcast optics, the URSA Mini B4 Mount provides a seamless and optically corrected pathway to integrate these two worlds.