Linear Zoom Trigger is a cable with 3.5mm connector and button.
The "Linear zoom trigger" realizes zoom from the center point to assit quick focus.
Peaking focus – How to use Linear Zoom Trigger to Turn on “Peaking Focus”
After focusing, please press ZOOM key, the image will be zoomed-in; Press again to turn on
peaking focus, which assists the cameraman to quickly focus. Please press ZOOM key
again to turn off the Peaking Focus.