This HD grid is a warped polar coordinate grid. When projected onto the convex mirror, the resulting polar grid will appear on the dome. This grid allows the user to center the projected image on the mirror by moving the projector and using the controls on the secondary mirror mount. The operator then adjusts the position of the image on the dome by adjusting the tilt of the secondary mirror and the primary convex mirror. Some operators prefer a lower front spring line with the center of the projected image to the front of the center of the dome. Others prefer the image centered on the dome. Often whether the audience is on the floor or in chairs is the deciding factor.
Once the Newtonian™2 is adjusted for the specific use, it will retain this adjustment with closed and stored after use.