While using the middle mouse wheel to zoom in and zoom out in a drawing, Have you ever felt the middle mouse wheel zoom is too fast or too slow? That’s true. It can depend on the scale of the drawing and objects you are working on, or perhaps even your mood. This speed of the zoom in and out is controlled by a system variable named ZOOMFACTOR. The default of the system variable ZOOMFACTOR is 60. You type ZOOMFACTOR and then change the value. Don’t hesitate to have a try!