Cinema-grade Wireless Follow Focus Motor Damping Adjustment and A-B Point Travel Marking

1. The revolution of manual focus ring and wireless control follow focus

In professional film shooting, the photographer is only responsible for composing the shot and moving the lens, while the transition between virtual and real focus of the picture is fully controlled by the full-time first officer (1st AC - Focus Operator). The popularity of wireless follow focus systems allows individual mirrorless camera users to easily shoot Hollywood-level focus-changing blockbusters:

1. Pain points of traditional manual lens tightening:

• If you reach directly toward the lens to twist the focus ring, the gripping torque of your fingers will be directly transmitted to the camera body, causing the screen to shake violently and intolerably;
• Most of the focus rings of modern autofocus mirrorless lenses are electronic analog focus (Focus-by-Wire): there is no fixed linear physical correspondence between the physical angle of the rotating focus ring and the change in focal length. If you turn it slightly faster, the focus will fly off, making it impossible to accurately reproduce the focus point.

2. High-precision brushless servo motor:

• The drive motor is rigidly fixed on the side of the lens through a standard 15mm guide rail;
• The servo motor gear meshes with the focus gear ring of the lens, and is remotely driven by a handheld wireless follow focus handwheel via a 2.4GHz radio with ultra-low latency, achieving absolutely precise, linear, smooth and completely free of organic vibration focus flow.

2. Stepless follow focus gear ring (0.8 Mod) assembly and gear meshing to eliminate backlash

1. Industry standard gear module (Gear Pitch 0.8 Mod / 32 Pitch):

• Professional cinema lenses come with standard 0.8 module laser-engraved gears;
• Ordinary photography lenses (such as Sony GM, Canon RF) have smooth barrels and must be equipped with a high-quality seamless silicone or plastic snap-on Seamless Focus Gear Ring.

2. Gear bite clearance and backlash elimination specifications:

• Move the follow focus motor toward the lens to engage the two gears;
• Strength must be precise and moderate:
• Press too tight: The resistance of the motor increases sharply, causing sharp whistling during operation, which accelerates the wear of the motor gears and consumes the battery violently;
• Too loose bite: There is an obvious backlash when the handwheel rotates in the opposite direction. The handwheel has rotated 5 degrees but the lens does not move at all.
• Standard state: The two tooth surfaces are completely in contact with each other and there is no missing position. You can barely feel any shaking when gently opening the motor gear with your fingers. At the same time, you can gently turn the hand wheel with your hand to achieve smooth and silky damping.

3. Motor stroke automatic calibration (Auto Calibration) vs manual stroke limit (Manual Limit)

After powering on, the follow focus system must know the minimum focusing distance and the physical boundary of infinity of the lens:

1. Automatic calibration (applicable to film lenses/old lenses with physical hard limits):

• Long press the motor calibration button, the motor will automatically drive the gear to rotate at high speed in both clockwise and counterclockwise directions;
• When the lens rotates to infinity $\infty$ and the closest focus limit, the internal mechanical slot will generate a rigid block, and the motor detects the stall current peak (Stall Current) and automatically marks these two limit points as 0% and 100% physical end points.

2. Manual calibration (applicable to ordinary mirrorless lenses with electronic infinite rotation - extremely important!):

• The focus ring of an ordinary automatic mirrorless lens can rotate 360 degrees infinitely without any hard limit;
• If the automatic calibration is turned on directly, the motor will keep spinning and slipping wildly, unable to stop or even wear out the external gear ring!
• Manual marking process:
• Turn on manual calibration mode;
• Turn the handwheel, zoom in and observe through the screen, accurately aim the lens at infinity, and press and hold the mark button to confirm it is point A;
• Turn the handwheel in the opposite direction to the nearest focus point and confirm it as point B;
• The motor microcomputer automatically linearly maps the entire physical stroke of the handwheel within this virtual range, giving the stepless focus ring a perfect linear movie control feel.

4. A-B point focus memory (Focus Racking) actual lens operation

In film and television feature films, it is often necessary for the camera to quickly and accurately switch focus between the foreground character (point A) and the background dialogue character (point B):

1. Mark A-B electronic soft limit:

• Accurately focus on the eyes of the foreground protagonist and click the "Mark A" button on the handwheel;
• Turn the handwheel, move the focus accurately to the villain appearing outside the rear door, and click the "Mark B" button;
• At this time, the handwheel is electronically imposed with a virtual limit wall (Haptic Stop), and it will not cross these two targets no matter how it is turned.

2. Smooth focus shift (Rack Focus):

• During real shooting, the photographer does not need to look down at the focus scale on the screen. He only needs to rely on finger muscle memory to decisively and smoothly turn the handwheel from point A to the limit point B at the moment the actor drops his lines!
• The characters in the foreground of the picture are blurred from a clear and elegant blur to a creamy spot, and the villain in the background is in focus at the same moment as sharp as a scalpel. The whole process is done in one go, with 100% accuracy, completely eliminating the amateurish feeling of hesitantly pulling the bellows back and forth.

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