Orion 9968 instruction manual Collimating

	Secondary
	mirror
	Reflection of
Front of	your eye in
telescope	secondary
	mirror

Secondary	Reflection of
reflection of	inside of tube
inside of tube	(misalignment)

Figure 17a

Figure 17a. If the telescope’s optics are out of alignment the view through the rear opening of the telescope will resemble Figure‑2a.

	Secondary
	mirror
	Reflection of
Front of	your eye in
telescope	secondary
	mirror

Figure 17b

Figure 17b. With the optics properly aligned the view through the rear opening of the telescope will resemble Figure 2b.

Collimating

To collimate your telescope, remove the diagonal and eyepiece and look into rear opening of the tube (also remove the dust cover from the front of the tube). This should be done indoors, with the telescope pointed at a white wall in a well-lit room. Try to keep your eye centered with respect to the rear opening of the tube as best as possible. Using an Orion Collimating Eyepiece will aid greatly in keeping your eye centered and is strongly recommend.

Alternatively, you can make a crude collimating tool out of an empty, black plastic 35mm film canister. It will not have cross‑ hairs, so it won’t be as precise, but it will be better than noth‑ ing. Cut 1/2" from the top lip of the canister and put a 1/16" to 1/8" diameter hole in the center of its bottom. Insert the film canister collimating tool into the focuser like an eyepiece with the bottom end out.

Once you are ready to collimate, look into rear opening of the tube. If your telescope is out of collimation, it will resemble Figure 17a. A properly collimated scope will resemble Figure 17b. The direction of the misalignment in your telescope may differ from Figure 17a, but the diagram will give you the gen‑ eral idea of how things will look.

Note there are six alignment screws on the back of the opti‑ cal tube, three large and three small. You will need 4mm and 2.5mm Allen wrenches to turn these screws. These alignment screws push and pull the mirror cell in order to tilt it. When you loosen or tighten one of these screws, the other five screws must be adjusted as well to keep the proper amount of pres‑ sure on the back of the mirror cell. By making slight adjustments to how much the screws are tightened and loosened, you will change the alignment of the primary mirror.

Look into the rear opening of the tube and locate the black crescent that shows the telescope is out of alignment. (Figure 17a). Note which way the front of the telescope would need to move in order to “fill” that black crescent and resemble Figure 17b. Then look at the back end of the telescope and locate the alignment screw that is in the direction that the front of the telescope needs to move. For example, if the view in your telescope resembled Figure 17a, then you would want to move the front opening of the telescope scope to the right. The align‑ ment screw you would start with would be the screw on the right as shown in Figure 18.

Your actions now depend on whether this alignment screw is a small or large screw. Please note that you will be working to adjust the mirror cell by keeping all the screws not too loose and not too tight. Follow the steps listed below carefully and refer to the figures that accompany them.

	Figure 18. If the view through
Figure 3
	the rear opening of the telescope
	resembled Figure 17a, then the
	alignment screw you would start
	with would be this one. The actual
	first alignment screw you would
	pick will vary depending on which
	way the front opening would need
	to move in order to “fill” the black
	crescent.

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