How is variable zoom done?

[Artist]

The Autohotkey solution (using the North/South of a POV hat), assuming that <Ctrl>+<Insert> ("Control Insert") is assigned to Camera, Keys, "Hold to adjust Field of View":

#Persistent
iIdStick = 1
SetTimer, watchPOV_Stick, 5

watchPOV_Stick:
    bFirst := true
    while(true){
        GetKeyState, iPOV, %iIdStick%JoyPOV  ; Get position of the POV control.

        ; Some joysticks might have a smooth/continous POV rather than one in fixed increments.
        ; To support them all, use a range:
        if iPOV < 0                                            ; No angle to report
            break
        else if (iPOV > 31500) OR (iPOV >= 0 AND iPOV < 4500){      ; 315 to 360 to 45 degrees: Forward
            zoomViewIn(bFirst)
            bFirst := false
        }
        else if (iPOV >= 13500) AND (iPOV <= 22500){           ; 135 to 180 to 225 degrees: Backward
            zoomViewOut(bFirst)
            bFirst := false
        }
        else
            break
    }
    return

zoomViewOut(bFirst){
    if(bFirst){
        MouseMove 0, 1200, 0
    }
    Send !{Insert down}
    MouseMove 0, -1, 0, R
    Send !{Insert up}
    return 0
}    
zoomViewIn(bFirst){
    if(bFirst){
        MouseMove 0, 0, 0
    }
    Send !{Insert down}
    MouseMove 0, 1, 0, R
    Send !{Insert up}
    return 0
}

Artist