If you experience motors twitching or jumping during a focus pull then you will need to recalibrate the focus control knob.
It is also recommended that you update to the latest firmware.
To calibrate the focus knob go to MENU .... INPUTS ... RECAL KNOB .. then, do this exactly,
- Rotate the knob to near hard stop. Press set.
- Rotate the knob until the number gets near 3800 .. or near 100 ... (whichever comes first)
- Keep rotating, slow and smooth, don't stop. Imagine that you're doing a slowish rack. Not super slow.
- After the number "flips" (jumps), you can stop. Press set.
- Rotate to the far hard stop. Press set.
This should set the magnetic encoder calibration accurately! If it still isn't quite perfect, you can repeat the process... The main goal is to slowly and smoothly rotate over the "flip point", without lingering on it or going too fast/slow. once it's set accurately, it doesn't need to be done again.