Orion 9541, 9549, 9909 Specifications, Appendix a Collimating Aligning the Mirrors

Specifications

#9549 GoScope 80 TableTop

Optical design	Refractor
Objective lens	Achromatic, air-spaced, fully
	coated
Aperture	80mm
Focal length	350mm
Focal ratio	f/4.3
Diagonal	90° prism, accepts 1.25"
	eyepieces
Eyepieces	20mm eyepiece (18x) and
	10mm eyepiece (35x), fully
	coated, 1.25"
Finder scope	EZ Finder II reflex sight
Optical tube mounting block	Fits Orion Dovetail mounts
	and ¼"-20 photo tripods
Total weight	5.7 lbs. (tube 2.9 lbs, mount
	2.8 lbs)
#9909 StarMax 90 TableTop
Optical design	Maksutov-Cassegrain
Primary mirror coating	Aluminum with SiO2 overcoat
Meniscus lens coating	Anti-reflection multi-coatings
	on both sides of lens
Aperture	90mm
Focal length	1250mm
Focal ratio	f/13.9
Central obstruction diameter	29mm
Eyepiece adapter	Accepts 1.25" accessories,
	camera T-threads
Diagonal	90° mirror star diagonal, 1.25"
Eyepieces	25mm (50x) and 10mm
	(125x), fully coated
Finder scope	EZ Finder II reflex sight
Optical tube mounting block	Fits Orion Dovetail mounts
	and ¼"-20 photo tripods
Weight	6.5 lbs (tube 3.7 lbs, mount
	2.8 lbs)

#9541 SkyScanner 100 TableTop

Optical design	Reflector
Primary mirror	Parabolic
Primary mirror coating	Aluminum with SiO2 overcoat
Secondary mirror diameter
Aperture	100mm
Focal length	400mm
Focal ratio	f/4
Focuser	1.25" Rack & Pinion
Eyepieces	20mm (20x) and 10mm (40x)
	fully coated
Finder scope	EZ Finder II reflex sight
Optical tube mounting block	Fits Orion Dovetail mounts
	and ¼"-20 photo tripods
Weight	6.2 lbs (tube 3.4 lbs, mount
	2.8 lbs)

Appendix A: Collimating (Aligning the Mirrors)

Collimating is the process of adjusting the mirrors so they are perfectly aligned with one another. Your telescope’s optics were aligned at the factory, and should not need much adjust- ment unless the telescope is handled roughly. It is only rec- ommended you make changes if the telescope is grossly out of alignment. Slight variations should still provide acceptable viewing under most conditions.

To check collimation (mirror alignment), remove the eyepiece and look down the focuser. You should see the secondary mirror centered in the drawtube, as well as the reflection of the primary mirror centered in the secondary mirror, and the reflection of the secondary mirror (and your eye) centered in the reflection of the primary mirror, as in.

Star-Testing the Telescope

When it is dark, point the telescope at a bright star and accu- rately center it in the eyepiece’s field of view. Slowly de-focus the image with the focusing knob. If the telescope is correctly collimated, the expanding disk should be a perfect circle. If the image is unsymmetrical, the scope is out of collimation. The dark shadow cast by the secondary mirror should appear in the very center of the out-of-focus circle, like the hole in a donut. If the “hole” appears off-center, the telescope is out of collimation.

NOTE: If you try the star test and the bright star you have selected is not accurately centered in the eyepiece, the optics will always appear out of collimation, even though they may be perfectly aligned. It is critical to keep the star centered, so over time you will need to make slight cor- rections to the telescope’s position in order to account for the sky’s apparent motion.

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