public void setZoomOutTrigger(Trigger... triggers) {
        inputManager.deleteMapping(CameraInput.CHASECAM_ZOOMOUT);
        inputManager.addMapping(CameraInput.CHASECAM_ZOOMOUT, triggers);
        inputManager.addListener(this, CameraInput.CHASECAM_ZOOMOUT);
    }
Sets custom triggers for zooming out the cam
default is
new MouseAxisTrigger(MouseInput.AXIS_WHEEL, false)  mouse wheel down

@param triggers the triggers to assign
jme3-core/src/main/java/com/jme3/input/ChaseCamera.java