ARRI focus motor with 18-bit resolution, 32,000 focus positions, and automatic lens detection via LDS-2 for precise follow-focus control.
Technical Details
The cforce motor weighs 490 grams and measures 96 × 76 × 58 mm. The gearbox operates with a gear ratio of 1:156 and achieves speeds of 1 to 360°/second. The motor features integrated encoders with 18-bit resolution and supports 12V and 24V power supply. The system automatically recognizes lens types through LDS-2 (Lens Data System) communication and can store up to 32,000 focus positions. The operating temperature range is between -20°C and +55°C.
The cforce plus additionally offers LBUS connectivity and extended torque modes for heavy cine lenses. Both variants operate with a noise level below 25 dB(A) at a distance of one meter.
History & Development
ARRI introduced the cforce system in 2016 as the successor to the cforce mini, to meet the increasing demands of digital cinema productions. The development occurred in parallel with the ALEXA Mini and aimed at compact, modular camera rigs. In 2018, the cforce plus followed with expanded compatibility for third-party systems.
The system arose from the need to support handheld camera setups and complex gimbal configurations without losing the precision of traditional follow-focus systems.
Practical Use in Film
The cforce enables manual focusing via handwheels and fully automated focus pulls through programmable A/B points. In "Blade Runner 2049" (2017), Roger Deakins used the system for precise focus shifts in complex Steadicam sequences. The automatic lens mapping function significantly reduces setup times, as no manual calibration is required.
The system supports multicam productions through synchronous control of multiple motors via the Hi-5 hand unit. The low-noise operation of the brushless motor proves particularly beneficial in available-light shoots.
Comparison & Alternatives
Unlike traditional follow-focus systems, the cforce offers full integration into ARRI's ecosystem with automatic metadata transmission. Preston FIZ systems achieve comparable precision but require separate radio links. Tilta motors offer more affordable alternatives for budget productions but do not reach the resolution of the cforce system.
The RT Motion FIZ remains the standard for high-end productions with complex multi-axis requirements, while the cforce is optimally suited for ARRI-based workflows with medium to large budgets.