2013Follow Focus forum
Motorized focus system speed limitations for rapid focus pulls on cinema lenses
13 years old. Gear and prices may have changed since.
DisputedParticipants disagreed and reached no conclusion. Read the findings as positions, not as an answer.
What the thread found
- A DM1X motor reached its maximum speed and could not complete a 9 inches to 4 feet focus pull on a 32mm Zeiss Close Focus Prime in 1.5 seconds at 120 frames per second, requiring the move to be slowed down instead.
- The Zeiss Close Focus Prime exhibits significantly greater focus throw than standard primes, with at least triple the rotation needed when focusing at close distances.
- Alternative faster focus motor options mentioned include the DM2, Heden motors, and Axis1 systems.
- Manual focus techniques using a speed crank or tape-based mechanical stop can achieve rapid focus pulls without motor limitations.
- Increasing motor speed through gearing modifications would require either enlarging the motor's drive gear or implementing a gear reduction system with differently sized gears on a single shaft.
- The DM1X motor performs better with stiff lenses compared to friction-free lenses when considering overall speed performance.
Depends on
- The specific performance comparison between motor systems with friction-free versus standard lenses remains unclear.
- Gearing modification solutions were discussed only hypothetically and no successful implementation was documented.
- The exact specifications of alternative motors like the Axis1 were not detailed.
- Manual focus speed and accuracy for such rapid moves would depend on operator skill and the specific lens characteristics.