Meade 12.5 instruction manual Correct Collimation, Spider Vane Adjustments, Face-onview

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Fig. 4: Newtonian Reflecting Telescope. (1) Spider Vanes; (2) Secondary Mirror; (3) Parabolic Primary Mirror; (4) Primary Mirror Hex Screws;

(5) Focuser Drawtube; (6) Focused Image.

Face-on view Edge-on view

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Fig. 5: Secondary Mirror Assembly. (1) Spider Vanes; (2) Tilt Screws; (3)Secondary Mirror Holder.

Correct Collimation

A properly collimated (aligned) mirror system in your Starfinder Dobsonian telescope assures the sharpest images possible. Your Starfinder is properly aligned when the primary mirror

(3, Fig. 4) and secondary mirror (2, Fig. 4) are tilted so that the focused image (6, Fig. 4) falls directly through the center of the focuser drawtube (5, Fig. 4).

To inspect the view of the mirror collimation, remove the eyepiece and look down the focuser drawtube. The round edge of the focuser drawtube (1, Fig. 6) will frame the reflections of the primary mirror with the secondary mirror (2, Fig. 6) the spider vanes (3, Fig. 6) and your eye (4, Fig. 6). Properly aligned, all of these reflections will appear concentric (i.e. centered) as illustrated in Fig. 6. Any deviation from the concentric reflections will require adjustments to the secondary mirror assembly (Fig. 5), and/or the primary mirror cell.

Spider Vane Adjustments

Looking down the open end of the telescope tube, check to see if the secondary mirror system is centered in the optical tube. If the assembly is off-center, loosen one of the spider vane adjustment/lock knobs while unscrewing the opposite knob. Only make adjustments to 2 knobs at a time until the secondary mirror is centered in the drawtube. When the spider vane is correctly positioned, the view through the drawtube will look like

Fig. 6: Correct Collimation. (1) Round Edge of Focuser Drawtube;	Fig. 8: Secondary Mirror Misalignment. (1) Secondary Mirror;
2) Secondary Mirror; (3) Spider Vanes; (4) Eye.	(2) Round Edge of Focuser Drawtube; (3) Reflection of Primary Mirror.

Fig. 7: Spider Vane Misalignment. (1) Secondary Mirror; (2) Round	Fig. 9: Primary Mirror Misalignment. (1) Secondary Mirror; (2) Round
Edge of Focuser Drawtube.	Edge of Focuser Drawtube; (3) Eye.