Anti-backlash
– All mechanical gears have a certain amount of backlash or play between the gears. This
play is evident by how long it takes for a star to move in the eyepiece when the hand control arrow buttons are
pressed (especially when changing directions). The CGE anti-backlash features allows the user to compensate
for backlash by inputting a value which quickly rewinds the motors just enough to eliminate the play between
gears. The amount of compensation needed depends on the slewing rate selected; the slower the slewing rate
the longer it will take for the star to appear to move in the eyepiece. There are two values for each axis, positive
and negative. Positive is the amount of compensation applied when you press the button, in order to get the
gears moving quickly without a long pause. Negative is the amount of compensation applied when you release
the button, winding the motors back in the other direction to resume tracking.
Normally both values should be
e same. You will need to experiment with different values (from 0-99); a value between 20 and 50 is usually
sults in a pause when pressing the
tton, go with the higher value for positive, but use a lower value for negative. The telescope will remember
a mountainous location where the horizon is partially
bscured, you can set your minimum altitude limit to read +20º. This will make sure that the hand control only
displays objects that are higher in altitude than 20º.
lore the entire object database, set the maximum altitude limit to 90º and the minimum limit
–90º. This will display every object in the database lists regardless of whether it is visible in the sky from
tton direction to positive will move the telescope in the same direction
at the telescope tracks (i.e. towards the west). Setting the altitude buttons to positive will move the telescope
in declination.
eclination Goto approach will only apply while the telescope tube is on one side of the Meridian. Once the
o change the Goto approach direction, simply choose
Goto Approach
from the
Scope Setup
menu, select
he telescope approaches its alignment
ar from the west (negative azimuth) and clockwise (negative altitude) then make sure that the buttons used to
center the alignment stars also move the telescope in the same directions.
th
best for most visual observing, whereas a higher value may be necessary for photographic guiding.
To set the anti-backlash value, scroll down to the
anti-backlash
option and press ENTER. While viewing an
object in the eyepiece, observe the responsiveness of each of the four arrow buttons. Note which directions you
see a pause in the star movement after the button has been pressed. Working one axis at a time, adjust the
backlash settings high enough to cause immediate movement without resulting in a pronounced jump when
pressing or releasing the button. Now, enter the same values for both positive and negative directions. If you
notice a jump when releasing the button, but setting the values lower re
bu
these values and use them each time it is turned on until they are changed.
Filter Limits
– When an alignment is complete, the telescope automatically knows which celestial objects are
above the horizon. As a result, when scrolling through the database lists (or selecting the Tour function), the
hand control will display only those objects that are known to be above the horizon when you are observing.
You can customize the object database by selecting altitude limits that are appropriate for your location and
situation. For example, if you are observing from
o
If you want to exp
Observing
Tip!
to
your location.
Direction Buttons –
The direction a star appears to move in the eyepiece changes depending on which side of
the Meridian the telescope tube is on. This can create confusion especially when guiding on a star when doing
astrophotography. To compensate for this, the direction of the drive control keys can be changed. To reverse
the button logic of the hand control, press the MENU button and select
Direction Buttons
from the Utilities
menu. Use the Up/Down arrow keys (10) to select either the Declination (north and south) or Right Ascension
(east and west) button directions and press ENTER. Select either positive or negative for both axes and press
ENTER to save. Setting the azimuth bu
th
counterclockwise along the DEC axis.
Goto Approach -
lets the user define the direction that the telescope will approach when slewing to an object.
This allows the user the ability to minimize the affects of backlash when slewing from object to object. Just
like with
Direction Buttons
, setting
GoTo Approach
to positive will make the telescope approach an object
from the same direction as tracking (west) for Right Ascension (RA) and counterclockwise
D
tube passes over to the other side of the Meridian, the Goto approach will need to be reversed.
T
either Altitude or Azimuth approach, choose positive or negative and press ENTER.
In order to minimize the affect of gear backlash on pointing accuracy, the settings for
Button Direction
should
ideally match the settings for
GoTo Approach
. By default, using the up and right direction buttons to center
alignment stars will automatically eliminate much of the backlash in the gears. If you change the Goto
approach of your telescope it is not necessary to change the Button Direction as well. Simply take notice of the
direction the telescope moves when completing it final goto approach. If t
Helpful
Hint!
st
