Orion 3 EQ Appendix a Collimation Aligning Mirrors, Collimation Cap Mirror Center Mark

Figure 8. Collimating the optics. (a) When the mirrors are properly aligned, the view down the focuser drawtube should look like this. (b) With the collimation cap in place, if the optics are out of alignment, the view might look something like this. (c) Here, the secondary mirror is centered under the focuser, but it needs to be adjusted (tilted) so that the entire primary mirror is visible. (d) The secondary mirror is correctly aligned, but the primary mirror still needs adjustment. When the primary mirror is correctly aligned, the “dot” will be centered, as in (e).

Appendix A:

Collimation—

Aligning the

Mirrors

Collimation is the process of
adjusting the mirrors so they
are perfectly aligned with one
another.	Your		telescope’s
optics were aligned at the fac-
tory, and should not need
much adjustment unless the
telescope is handled roughly.
Accurate mirror alignment is
important to ensure the peak
performance		of	your tele-
				a.
scope, so it should be
checked regularly. Collimation
is relatively easy to do and
can be done in daylight.
To check collimation, remove
the eyepiece and look down
the focuser		drawtube. You
should	see	the	secondary
mirror centered in the draw-
tube, as well as the reflection				b.

of the primary mirror centered in the secondary mirror, and the reflection of the second- ary mirror (and your eye) cen- tered in the reflection of the primary mirror, as in Figure 8a. If anything is off-center, proceed with the following col- limation procedure.

d.

The Collimation Cap

and Mirror Center Mark

Your SpaceProbe 3 comes with a collimation cap. This is a simple cap that fits on the focuser drawtube like a dust cap, but has a hole in the cen- ter and a silver bottom. This helps center your eye so that collimation is easy to perform. Figures 8b through 8e assume

you have the collimation cap in place.

In addition to providing the collimation cap, you’ll notice a tiny ring (sticker) in the exact center of the primary mirror. This “center mark” allows you to achieve a very precise collimation of the primary mirror; you don’t have to guess where the cen- ter of the mirror is. You simply adjust the mirror position (described below) until the reflection of the hole in the collima-

	tion cap is centered inside
	the ring. This center mark is
	also required for best results
	with	other	collimating
	devices,	such	as	Orion’s
	LaserMate Laser Collimator,
	obviating the need to remove
	the primary mirror and mark it
	yourself.
	NOTE:	The	center		ring
	sticker need not ever be
	removed from the primary
	mirror.	Because		it	lies
	directly in the shadow of
	the secondary mirror, its
	presence in no way ad-
	versely affects the optical
	performance of the tele-
	scope or the image quality.
	That might seem counter-
	intuitive, but it’s true!
	Aligning the
	Secondary Mirror
	With the collimation cap in
	place, look through the hole
	in the cap at the secondary
	(diagonal) mirror. Ignore the
c.
	reflections for the time being.
	The secondary mirror				itself
	should be centered in the
	focuser	drawtube,		in	the
	direction parallel to the length
	of the telescope. If it isn’t, as
	in Figure 8b, it must be
	adjusted. This adjustment will
	rarely, if ever,		need to be
e.
	done. It helps to adjust the
	secondary mirror in a brightly
	lit room with the telescope
	pointed toward a bright sur-
	face, such as white paper or
	wall. Placing a piece of white
	paper in the telescope tube
	opposite the focuser (i.e., on
	the other side of the second-
	ary mirror) will also be helpful
	in collimating the secondary
	mirror. Use a		small	Phillips

head screwdriver to loosen the three small alignment screws in the center hub of the 3-vaned spider several turns. Now hold the mirror holder stationary (be careful not to touch the surface of the mirrors), while turning the center screw with a larger Phillips head screwdriver (see Figure 9). Turning the screw clockwise will move the secondary mirror toward the front opening of the optical tube, while turning the screw

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