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" Dual-Speed Low-Profile Crayford focuser provides the most focus range for accessories that require extra in- travel. With a minimum focus height of 43mm, this focuser is an excellent choice for any astrophotographic system. The strong machined aluminum construction supports heavy 2" eyepieces as well as heavy camera bodies. The smooth focus motion and fine-focus wheel allow precision adjust- ments for critical focusing of eyepieces and cameras.
Installation
This focuser was designed to be a “drop-in” replacement for the 2" focuser that comes standard on Orion 8" and 10" reflectors, including IntelliScope and Classic Dobsonians. If you have one of these telescopes, installing the 2" Crayford will be easy. You will need a Phillips head screwdriver and an adjustable crescent wrench or pliers. Use the following procedure:
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" dual-speed low-profile Crayford focuser where the other focuser was previously. Orient the focuser the same as the removed one was. The through holes in the base of the focuser should line up with the holes in the telescope tube.
Drawtube extension thumbscrew
Fine focus wheel