Specifications, Orion 8 f/4.0 Newtonian Astrograph

the Phillips-head screw is unthreaded, the secondary mirror and its holder can be removed from the telescope. The sec- ondary mirror does not need to be removed from its holder for cleaning. Then follow the same procedure described below for cleaning the primary mirror.

To clean the primary mirror, first carefully remove the mirror cell from the telescope. To do so you must remove the six screws on the exterior of the mirror cell (Figure 15). Then pull the cell away from the tube. You will notice the primary mirror is held in the mirror cell with three clips held by two screws each. Loosen the screws and remove the clips.

You may now remove the primary mirror from its cell. Do not touch the surface of the mirror with your fingers. Lift the mirror carefully by the edges. Set the mirror on a clean soft towel. Fill a clean sink or large bucket with room temperature water, a few drops of liquid dishwashing detergent, and if possible, a capful of 100% isopropyl alcohol. Submerge the mirror (alu- minized surface facing up) in the water and let it soak for a few minutes (or hours if it’s a very dirty mirror). Wipe the mir- ror under water with clean cotton balls, using extremely light pressure and stroking in straight lines across the mirror sur- face. Use one ball for each wipe across the mirror. Then rinse the mirror under a stream of lukewarm water. Any particles on the surface can be swabbed gently with a series of cotton balls, each used just one time. Dry the mirror surface with a stream of air (a “blower bulb” works great). Cover the mirror surface with tissue, and leave the mirror in a warm area until it is completely dry before placing it back in the mirror cell. Then reinstall the mirror cell in the telescope optical tube with the six screws.

Specifications

Orion® 8" f/4.0 Newtonian Astrograph

Optical configuration: Newtonian reflector

Aperture:	200mm
Focal length:	800mm
Focal ratio:	f/4.0
Primary mirror:	BK-7 optical glass, parabolic figure
Mirror coatings:	Enhanced aluminum (>91%
	reflectivity) with SiO2 overcoat
Secondary
mirror minor axis:	70mm
Focuser:	Machined aluminum, dual-speed
	(10:1) Crayford with linear track
	bearing, accepts 1.25" or 2"
	accessories
Drawtube travel:	50mm
Optical tube:	Rolled steel, gloss enamel exterior
	finish
Outside diameter:	229mm (9.0")
Weight:	7.3 kg (16.0 lbs.)
Length:	69.7cm (27.5")
Tube rings:	Included, hinged, felt-lined
Finder Scope:	8x50, with spring-loaded X-Y dovetail
	bracket
Extension tube:	35mm length, 2" compression ring
	holder