40
6. Stop selection on 3 (or any other number you choose). We recommend that you start with 3 if you are beginning
your adjustment.
7. While viewing a star at high power through an eyepiece, use the E–W buttons to test this setting at 12x. With
the proper backlash setting, the star will appear to stop moving right when the button is released. Too high a setting will
cause the star to jump back a bit. If this happens select the previous number. You can now test this with out leaving the
Mount Move Limits menu.
8. Repeat process, increasing or decreasing the RA Backlash setting by 1 each time to evaluate changes.
9. The number will remain in permanent memory and will not need to be set again.
The R.A. and Dec. backlash settings are retained in the Keypad memory. Each time you initialize the mount with the
Keypad, these values are sent to the ROM chip in the GTO control box. The amount of backlash can vary depending
on load and orientation of the telescope. It can never be precisely set, so there will always be a small delay or small
overshoot.
Declination Backlash Adjustment (for Visual Observers)
When using the 1x, 0.5x and 0.25x guide rates in declination, you may nd that there is a delay when attempting to reverse
the motion of the star. Normally declination drift is only in one direction and will require correction with only one button.
However, occasionally it may be necessary to reverse the motion. The multiple gear trains inside the drive motors take
a number of encoder pulses to unwind and rewind in the opposite direction. To compensate for this, we have included
a circuit that pulses the motor very rapidly for a moment before continuing at the slower rate. Because the delay varies
with each motor, we have programmed a 10-position adjustment, which can be used to dial in the exact amount of
compensation.
Very Important Note: Always choose the 1x guide setting when calibrating and guiding with a guide camera. Not
doing so can create instability and cause the guiding corrections to continually overshoot. Also be sure that
backlash compensation is set to zero in the keypad and in any computer software.
1. At Main Menu, press “6=B”. This controls the speed of your N-S-E-W directional buttons. Continue to press 6 to
scroll (toggle) through choices. You can also access your button speed anywhere you can use them by pressing the
“±” button and using the Button rate menu.
2. Select 0.25x.
3. Choose “2=Setup” from the Main Menu.
4. Choose “2=Mount Move Limits” from the Setup menu.
5. Press “2=DEC Backlash”. As you continue to press “2”, the number eld will scroll 0–9.
6. Stop selection on “3” (or any other number you choose). We recommend that you start with “3” if you are begin-
ning your adjustment.
7. While viewing a star at high power through an eyepiece, use the N-S buttons to test this setting at 0.25x. You
have set the compensation number correctly when the telescope will move almost instantaneously when reversing the
direction in declination. You can now test this with out leaving the Mount Move Limits menu.
8. Repeat process, increasing DEC Backlash setting by “1” each time to evaluate changes.
9. The number will remain in permanent memory and will not need to be set again.
Normally, Dec. backlash is adjusted only for manual guided astrophotography where the scope is always in one orientation
for a long time. Even here, a different adjustment may be needed in different parts of the sky.
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