Meade Telescope, LXD 75 instruction manual Polar Alignment Viewfinder, Enhancement Methods

Reticle LED Knob

Eyepiece

Fig. 43: The polar alignment viewfinder.

Fig. 44: The view inside the polar alignment viewfinder reticle.

APPENDIX B: ENHANCING POINTING PRECISION

The Polar Alignment Viewfinder

Typically Autostar's pointing capabilities are sufficient for most telescope observers, and the use of the polar alignment viewfinder is unnecessary for them. However, for those observers who need to meet the more demanding requirements of astropho- tography, the polar alignment viewfinder allows the telescope mount to be more pre- cisely aligned with true North. The polar alignment viewfinder contains a reticle, lit by an LED (Figs. 43 and 44).

To align your telescope to North using the polar alignment viewfinder:

1.Set your telescope in the home position (see page 17). Then loosen the Dec. lock (17, Fig. 1d) and rotate the optical tube 90°. Re-tighten the Dec. Lock.

2.Loosen the R.A. Lock (33, Fig. 1d).

3.Remove the polar viewfinder cap (18, Fig. 1d).

4.If you have not already done so, remove the plastic separating the watch batter- ies inside the polar alignment reticle. See step 12, page 13.

5.Turn the polar alignment reticle LED knob to turn on the LED and look through the reticle.

6.Northern Hemisphere: Move the telescope mount until Polaris is superimposed on the graduated area of the reticle (between 40' and 60'). The center crosshair denotes the North celestial pole. Southern Hemisphere: The four-sided figure in the reticle represents a grouping of four stars in Octantis (Sigma, Tau, Chi, and Upsilon) for use in the Southern Hemisphere. Move the telescope mount on its R.A. axis until the four stars depicted in the reticle are superimposed on the four star group that matches the reticle pattern.

7.Use the latitude T-handle screws (26, Fig. 1d) and the fine azimuth control knobs (27, Fig. 1d) to fine tune the mount adjustment until the reticle pattern is more precisely superimposed over the appropriate position as described in step 6.

Note: Not all pointing positions are possible with the polar alignment reticle, as the tripod is a limiting factor as to how far the optical tube and mount can be moved.

8.Tighten the R.A. Lock (33, Fig. 1d). Return the optical tube to the home position. Note: Remember to turn off the polar alignment reticle LED.

Enhancement Methods

Autostar provides four methods of enhancing your telescope’s pointing precision:

#1: Three-Star Alignment, #2: Axis Alignment #3: Axis Alignment with Autostar and

#4: Smart Drive Training (Periodic Error Correction).

Method #1 is recommended for all users, but especially for the beginner and Methods #2, #3 and #4 are recommended for the Advanced observer.

Method #1: Three-Star Alignment Using Autostar

Perform this procedure at night. This method is similar to Two-Star Alignment (see page 51), but in this method, Autostar chooses three stars to align upon: Two stars on one side of the sky and a third star on the opposite side of the sky.

In order to get the most out of this procedure, make sure you perform the Train the Drive procedure (see page 20). The combination of Training your Drive and perform- ing Three-Star Alignment will optimize your pointing accuracy.

To perform the Three-Star Alignment:

1.Keep pressing MODE until "Select Item: Setup" is displayed. Press ENTER.

2."Setup: Align" displays. Press ENTER. "Align: Easy" displays. Press the Scroll

Down key until “Align: Three-Star” displays. Press ENTER.

3."German North" displays and a scrolling message prompts you to set your telescope in the polar home position. See SETTING THE POLAR HOME POSITION, page 17, for a description of this procedure. Press ENTER after you finish the procedure.