Orion 13032 instruction manual Installation, Usage, Fine Focus

Congratulations on your purchase of a quality Orion 2" dual- speed Crayford focuser. This focuser is intended for use with the Orion

ED-80, ED-100, Astroview 100, 120ST and the SkyView Pro 120mm. If you do not have one of these refractors, 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 strong machined aluminum construction supports heavy 2" eyepieces as well as heavy camera bodies. The smooth focus motion and fi ne-focus wheel allow precision adjustments for critical focusing of eyepieces and cameras.

Installation

This focuser was designed to be a “drop-in” replacement for the refractors listed above. If you have one of these telescopes, installing the 2" Crayford will be easy. You will only need a Phillips head screwdriver. Use the following procedure:

1.Locate the three screws holding the existing focuser onto the tube wall. In the case of the larger 120mm refractors, locate the screws that hold the focuser to the optical tube adapter collar.

2.Remove these three screws, making sure to hold onto the focuser itself so it does not fall when the last screw is removed. Do not lose the screws as they will be required to install the new focuser.

3.Remove the 2" focuser from the tube.

4.Place the 2" dual-speed Crayford focuser where the other focuser was previously.

5.Install the three screw, and tighten the screws fi rmly.

Usage

Using the 2" dual-speed low-profi le Crayford focuser is very straightforward. Place your 2" eyepiece in the focuser drawtube, and secure it in place with the thumb- screw. Imaging cameras should generally utilize a 2" camera adapter when used with the focuser. Insert the camera adapter the same way as a 2" eyepiece. To focus, simply rotate one of the focus wheels.

The large focus lock thumbscrew near the focusing shaft (see Figure 1) locks the drawtube into position once focus has been achieved. This is especially useful when using a camera or heavy eyepiece in the focuser. Be sure this thumbscrew is loosened when focusing. The socket head set screws above the focus lock thumbscrew (see Figure 1) adjusts drawtube focusing tension. If a heavy eyepiece

Eyepiece thumbscrews

Focus wheel

Fine focus wheel

Focus lock knob

Drawtube tension adustment screws

Focus wheel

1.25" Eyepiece adapter

Figure 1. The Orion 2” dual-speed Crayford focuser for Orion Refractors.

causes the drawtube to move inward by itself (drawtube tension too loose), or the focus wheels are diffi cult to turn (drawtube tension too tight), then you will want to adjust these set screw. This requires the included hex keys. Slightly loosen the center screw, then slightly tighten the outer screws equally. Test for tension and repeat if necessary (or reverse the procedure if the tension is too tight).

Fine Focus

The focuser features dual speed adjustment with the fi ne focus wheel. This small black wheel located on the side of the right hand focus wheel allows precise focus adjustment at a ratio of 11:1, meaning one turn of the focus wheel equals eleven turns of the fi ne focus wheel. Use the focus wheels to achieve rough focus on your target object, then use the fi ne focus wheel to coax out even more detail. You’ll be amazed at the amount of detail fi ne focus adjustments allow you to view on targets such as the lunar surface, planets, double stars, as well as other celestial objects.

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