Newton mirrors without center marking

Most Newtonians have a center mark on the primary mirror. This is an adhesive ring, similar to the ones found in staplers, to reinforce the holes.

With Newtonian mirrors without a center mark, you have to work by eye. However, you can tell fairly accurately when you're approximately in the center with the laser. You can use the three mirror mounts as a guide.

If you need to be very precise, you have to remove the mirror and its mirror cell and use a ruler to determine the mirror center. A permanent marker can be used for marking.

We describe how we check and adjust here: http://www.teleskop-spezialisten.de/shop/Ueber-uns:::12.html