Meade LXD 750 Telescope User Manual


 
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pole star may be somewhat off-center in the eyepiece, showing
that an alignment error was made during the initial setup. Using
the Latitude adjustment knob and Azimuth control knob on the
LXD Equatorial Mount, center the pole star during each interval
exercise, then follow the rest of the routine.
1. From the ALIGN menu option in the TELESCOPE mode,
press the ENTER key.
2. Ignore the Keypad display instructions to return the
telescope to 90 degrees in Declination and 00 HA. Instead,
press the GOTO key and the CDS will slew to the calculated
position of where the pole star should be.
3. Using only the Latitude and Azimuth adjustments on
the LXD Equatorial Mount, re-center the pole star in the
field of view in the eyepiece.
4. Press the ENTER key, and the CDS will slew to a bright star
overhead. Center this star using the "N", "S", "E", or
"W" keys and press ENTER.
5. While waiting 15-20 minutes between alignment intervals,
the telescope may be used to observe.
6. After 15-20 minutes, repeat the process, beginning with
Step 1. This process may be repeated as often as desired
to obtain the highest accuracy. After each 15 minute
interval, the pole star becomes more accurately centered.
An optional illuminated reticle crosshair eyepiece makes the
job of centering the star easy.
NOTE: Pressing the MODE key at any point in the alignment
routine will abort the routine and exit to the top menu.
There may be situations when it is impossible to see the pole star
(e.g., something blocking your line of sight). In such an occasion,
follow the Precise Polar Alignment instructions in Appendix A of
this manual. You will require the use of an illuminated reticle
crosshair eyepiece to complete the task. Once finished, follow
the steps outlined below to access the Object Library.
3) SMART: The SMART menu file controls the CDS Smart Drive,
a system designed to eliminate the small errors induced by tiny
gear imperfections that tend to slightly speed up or slow down the
drive tracking speed. These gear imperfections occur in a
regular eight minute pattern, the time required for one rotation of
the worm. The CDS can be trained to remember the pattern of
these imperfections and automatically apply the corrections
needed. Use of the Smart Drive greatly enhances the tracking
characteristics of the CDS, thus simplifying guiding during
astrophotography.
The menu also has provisions for correcting Declination drift.
Smart Drive will retain its training, even after the telescope is
turned off. (Of course, it is possible to retrain the system or erase
the training, if desired.)
The SMART menu has five options. They are; LEARN,
UPDATE, ERASE, DEC LEARN, and DEC CORRECT. To train
the Smart Drive, the telescope must be equipped with an
illuminated reticle eyepiece. Be sure to train the Smart Drive in
the 60.1 Hz Quartz setting; the CDS is automatically set at 60.1
Hz at power up. Thereafter, you can adjust frequency setting in
the TIMER/ FREQ mode and still enjoy the periodic error
correction.
Training the SMART DRIVE:
Once polar alignment of your telescope has been completed, the
CDS is pointing the telescope to a bright star overhead, near the
Celestial Equator. This star may be used, or another, as long as
the chosen guide star is near 0 degrees in Declination and more
or less overhead in Right Ascension. Before beginning the
SMART DRIVE training, set the brightness and/or the pulse
rate of the illuminated reticle (see page 10, The RET Key) on
the chosen guide star and practice guiding (keeping the star
exactly centered in the eyepiece) for a few minutes. Then,
follow these steps:
1. While in the SMART menu, move the LCD arrow to
LEARN by using the PREV or NEXT key and press
ENTER.
2. Numbers appear next to the LEARN display. These
numbers will begin counting down to zero. The highest
number that can appear is 200. This number represents a
sector of the worm wheel. The sector changes every 2.4
seconds. The SMART DRIVE needs to find its beginning
sector before training can start. It will be necessary to wait
until the system counts down to zero to begin.
3. As the Keypad display approaches its beginning sector, a
beeping alerts you that training is about to commence. At
this point, begin guiding on the chosen guide star, using
the N, S, E, and W keys.
Atone will beep every few seconds throughout the training
session. Try to keep the star in the same location on the
crosshair during the ten minute training sequence.
4. After eight minutes, the beeping stops, indicating that the
training is over. The Smart Drive immediately starts
playing back your drive corrections automatically,
dramatically improving the R.A. drive tracking
characteristics.
If you wish to further refine the accuracy of the drive system,
move the LCD arrow to UPDATE and press ENTER and follow
the same instructions as above. This can be done in UPDATE
as many times as you wish. With each training, the Smart Drive
will average your training sequences.
If a mistake has been made in training (e.g. pushing E instead
of W), you can eliminate the memory by moving the LCD arrow
to ERASE and press ENTER.
DEC LEARN:
A star that drifts consistently North or South during guiding, can
also be corrected for. With a guide star centered in the
telescope's field of view, move the LCD arrow to DEC LEARN
and press ENTER. Begin making drive corrections
immediately by pressing any of the direction (N, S, E, W) keys
to keep the star on the crosshair of the guiding eyepiece. It is
suggested that you train in DEC LEARN for at least half of your
intended exposure time for an astrophoto. The longer you train,
the more accurate the DEC LEARN will be. Once the desired
time is finished, press ENTER and the training will cease.
The Smart Drive then determines how many key pushes
occurred in N and S and chooses the direction which received
more commands. It then averages the time between key
pushes in the chosen direction. In this way, the Smart Drive can
correct for Declination drift (should your polar alignment be
slightly off), or will allow you to more precisely guide on non-
stellar objects, such as comets, asteroids, etc.
To play back your DEC LEARN training, move the LCD arrow
to DEC CORRECT and press ENTER. To halt the play back
press ENTER again. To erase the DEC LEARN training, either
move the LCD arrow back to DEC LEARN and press ENTER
twice or turn the CDS off.
4) 12/24 HR: This menu selection of the TELESCOPE file
simply toggles between a twelve and twenty-four hour display
of local time in the Time Mode.