Home >> Science & Nature >> Astronomy

How to Attach Telescope Mirrors

The process of attaching a telescope mirror is one of the most important and tricky tasks you have to accomplish when building a Newtonian reflector telescope. The easiest way to attach a mirror is to buy a commercial mounting cell for the mirror size you've chosen for your telescope. When properly attached to the telescope, the mounting cell allows you to collimate the mirror. Collimation is the critical process of "aiming" the primary mirror at the secondary mirror.

Things You'll Need

Telescope mounting cell
Telescope tube
Drill and ¼-inch bit
Telescope mirror

Instructions

- 1
  Mark the telescope tube at the bottom of the tube where the cell will attach. Most cells have four metal mounting stubs with screw holes. Mark the four screw locations precisely so that the cell rests perpendicularly to the telescope tube and the cell's bottom is flush with the bottom of the tube.
- 2
  Drill holes for the screws, each at precisely the same distance from the lower edge of the tube. If you aren't sure of your ability to get the screw holes precisely positioned, cut a 1-inch slot for the screw running lengthwise to the tube on either side of the mark you made for the cell mounting screws.
- 3
  Set the mirror into the mounting saddle on the cell. Attach the clips to the mirror and tighten the screws evenly. Do not over-tighten to prevent the mirror from breaking.
- 4
  Slide the mirror and cell mount into the lower end of the telescope tube and screw the cell into place. Square it to the tube and tighten the mounting screws.
- 5
  Collimate the mirror if you've already installed the secondary mirror, spider and focuser. Otherwise, install these parts before collimating. Turn the adjustment screws on the base of the cell one at a time to change the angle of the mirror so that the reflected image from the open end of the tube strikes the center of the secondary mirror. Remove the eyepiece from the focuser tube and look straight down at the secondary mirror. The mirror is correctly adjusted when the secondary mirror appears to be centered in the open end of the tube.

Astronomy