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and press ENTER. The letters will revert to lower case,
indicating the High Precision Pointing option is now "off".
10) SLEW RATE: Option #10 in the TELESCOPE menu is for
changing the slew rate of the CDS telescope. Slowing down the
slew rate will result in less noise as the telescope moves and will
also use a little less power. To change the slew rate, follow these
steps:
1. Press the MODE key on the Keypad until the
TELESCOPE/OBJECT LIBRARY menu appears on the
display. The cursor should be next to the TELESCOPE
option - if not, then press the PREV key to move the cursor
up one space.
2. Press ENTER to select the TELESCOPE functions.
3. Press the PREV or NEXT keys to move the cursor to option
#10: SLEW RATE. On the right hand part of the display, the
number 8 is visible. This represents the current slew rate in
degrees per second.
Press the ENTER key to change the slew rate. Each successive
ENTER key press increments the slew rate by 1 degree per
second.
After setting the desired rate, press the MODE key to return to
the TELESCOPE / OBJECT LIBRARY menu.
Note: The slew rate is NOT stored in permanent memory and
needs to be reset each time the telescope is powered up. The
default slew rate is 8 degrees per second.
11) DEC BACKLASH COMPENSATION: When taking long
exposure astrophotographs, it is necessary to “guide” the
photograph to make sure the telescope is tracking perfectly,
otherwise stars will appear as ovals instead of pinpoints. This is
done by setting the CDS Keypad to the GUIDE speed,
monitoring the star location (e.g., with an off-axis guider and
illuminated reticle eyepiece), and making small corrections to the
telescope position by using the "N", "S", "E", and "W" keys.
When making these corrections, the R.A. motor will speed up or
slow down (by pressing the “E” and “W” keys). The Declination
motor, however, when activated (by pressing the “N” and “S”
keys) will actually stop and reverse direction. Because of
backlash in the Declination motor gearbox, there will be a few
seconds delay before the telescope begins to move when
reversing direction.
The Dec backlash feature compensates for the Dec motor
gearbox backlash and provides instant telescope movement
when the motor direction is reversed. To program the Dec
backlash, use the following procedure:
1. Move to option #11 from the TELESCOPE menu. The
Keypad display will show:
11) BACKLASH 00
3. The GUIDE speed for the Declination motor is 15 arc-
seconds per second. Therefore, multiply the number of
seconds delay by 15.
4. Press and hold the ENTER key for 1 second. The Keypad
will beep and a blinking cursor will appear on the Keypad
display. Enter the number determined in step 3, above.
Press ENTER when the number is entered.
5. Check the time delay as described in Step 2, above. If there
is still a time delay, then increase the compensation number.
If there is a slight jump when reversing direction, then the
number is too large.
When the compensation number is correct, the CDS
telescope will move almost instantly when reversing the
direction in Declination. This number is stored in permanent
memory and should never need to be set again.
12) PIER: When the telescope is mounted on the Standard Field
Tripod, areas of the sky straight up are restricted because the
tube may hit the tripod legs. Selecting "Pier" will turn off this
restriction, allowing the telescope to slew to the zenith (straight
up) when the telescope is mounted on a pier.
B. OBJECT LIBRARY Menu File
The OBJECT LIBRARY menu file is the other half of the
TELESCOPE/OBJECT LIBRARY mode. With it, you can
become a tourist of the sky, or conduct research surveys of the
64,359 library objects. The CDS Object Library is accessible in
the most user friendly system ever designed for observers and
astrophotographers.
The position epoch of these objects is for real time, updated
every time you turn on your CDS. Even the planet’s positions
have their orbits calculated! This not only qualifies the CDS as
the most accurate integrated object library available, it will never
require updated software for precession of the stars or planetary
orbital changes.
There are three primary ways to use the Object Library: directly
accessing the library by using the M, STAR, or CNGC keys and
entering a specific catalog number; the START FIND option to
logically find a custom-tailored list of objects in organized strips of
the sky; or scanning the sky and have the Object Library tell you
what is in the field of view of the eyepiece by using the FIELD
option. Below is a description of the four OBJECT LIBRARY
menu files and file options.
To access the OBJECT LIBRARY menu file, move the LCD arrow
to the OBJECT LIBRARY display by pressing the PREV or NEXT
key while in the TELESCOPE/OBJECT LIBRARY mode and
press the ENTER key. Any of the four menu selections within the
OBJECT LIBRARY may be accessed by moving the LCD arrow
to the desired menu selection (using the PREV or NEXT keys)
and following these procedures:
1) OBJECT INFO
Press the ENTER key to read the type, brightness, size, and
visual quality of a chosen object. Press ENTER again to read the
R.A. and Dec coordinates. Press ENTER once more to
determine how far off the telescope is pointing from the chosen
object. The distance from the object is represented by a series
of LCD bars (each bar represents 10 degrees.) As the telescope
moves closer to the target object, the number of visible bars
decrease. When the telescope is pointing at the selected object,
all the bars disappear. The object information can also be
accessed at any time by entering the object's library number
Display 23
The “00” in the display shows the number of arc-seconds of
backlash the CDS is set to compensate for (the default
setting is 0 arc-seconds).
2. While observing a star at high power, time the Declination
movement delay when reversing the motor directions (by
pressing the “N” and “S” keys). Typical values are 2 to 4
seconds.