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Orion 2"
for Newtonian Reflectors
#8881 | 1.25" eyepiece adapter |
Eyepiece thumbscrew
Focus wheel
Drawtube extension thumbscrew
Drawtube tension adjustment screw
Focus wheel
Focus lock thumbscrew
Fine focus wheel
Figure 1. The Orion 2" dual-speed low-profile Crayford focuser for Newtonian reflectors.
Congratulations on your purchase of a quality Orion 2" dual- speed low-profile Crayford focuser. This focuser is intended for use with 6" to 12" aperture Newtonian reflectors. If you do not have a Newtonian reflector, the focuser may not be appropriate for your telescope.
Crayford focusers generally perform better than rack-and- pinion models because the design eliminates “focus shift”. Focus shift is when an image moves position in the eyepiece when it is being focused. This is very hard to eliminate in rack-and-pinon focusers due to slight gear and tolerance imperfections which cause the drawtube to move slightly left or right when focusing. For the Crayford design, the drawtube is constantly tensioned (by the focusing shaft and four “roller bearings”) so the drawtube cannot move perpendicular to the desired motion.
The 2"
Installation
This focuser was designed to be a
1.Position your Newtonian reflector optical tube so it is hori- zontal. This will prevent any screws or nuts from falling onto the primary mirror.
2.From the inside of the tube, secure one of the four focuser securing nuts with the wrench or pliers.
3.Use the screwdriver to completely unthread the focuser attachment screw from the securing nut currently being held by the wrench or pliers.
4.Repeat this for the other three nut and screw pairs.
5.Remove the 2" focuser from the tube.
6.Place the 2"
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IN 316 Rev B 02/09