Orion 3640 Collimating Telescope Eyepiece

To get the best images from your Newtonian or Dobsonian reflector telescope, its optics must be in precise alignment. This economical Collimating Eyepiece tool will ensure that your telescope's optics are aligned properly. This combination sight tube and Cheshire eyepiece consists of a 5"-long tube made of black-anodized aluminum. It fits in a telescope's 1.25" eyepiece holder. A peephole in the top and wire crosshairs at the bottom enable precise centering of Newtonian reflector telescope optical components. The polished 45-degree internal surface projects a ring, or annulus, of light into the optical path to facilitate precise primary mirror alignment. Simply insert the Orion Collimating Eyepiece in the telescope focuser drawtube and follow normal collimation steps. Your Newtonian reflector will always be in excellent optical alignment! Instructions included.