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5.4.12. Set RA Guiding (CEM25EC Only)
You can turn off R.A. guiding by selecting “
Filter R.A. Guiding
” to allow the high precision encoder
to correct the tracking error, or turn the R.A. guiding on by selecting “
Allow
RA Guiding
” to allow the mount
to receive guiding corrections from the autoguiding software.
5.5. Electric Focuser
This function controls an iOptron electric focuser.
5.6. PEC Option
PEC for short, is a system that improves the tracking accuracy of the drive by reducing the number
of user corrections needed to keep a guide star centered in the eyepiece. PEC is designed to improve
photographic quality by reducing the amplitude of the worm errors. Using the PEC function is a three-step
process. First, the system needs to know the current position of its worm gear so that it has a reference
when playing back the recorded error. Next, you must guide for at least 10 minutes during which time the
system records the correction you make. (It takes the worm gear 10 minutes to make one complete
revolution). This “teaches” the system the characteristics of the worm. The periodic error of the worm gear
drive will be stored in the hand controller and used to correct periodic error. The last step is to play back the
corrections you made during the recording phase. Keep in mind, the PEC only compensate the RA worm
error.
5.6.1. PEC Playback
You can turn “
PEC Playback On
” while you do the tracking, especially for long time astro-
photography. The default status is
PEC Playback Off
when the mount is turned on.
5.6.2. Record PEC
Here’s how to record the PE curve manually:
1. Find a bright star relatively close to the object you want to photograph.
2. Insert a high power eyepiece with illuminated cross hairs into your telescope. Orient the guiding
eyepiece cross hairs so that one is parallel to the declination while the other is parallel to the R.A. axis.
3. Center the guide star on the illuminated cross hairs, focus the telescope, and study the periodic
movement.
4. Before actually recording the periodic error, take a few minutes to practice guiding. Set the hand
control slew rate to an appropriate slew rate and practice centering the guide star in the cross hairs for
several minutes. This will help you familiarize yourself with the periodic error of the drive and the operation
of the hand control. Remember to ignore declination drift when programming the PEC.
5. To begin recording the drive's periodic error, press the
MENU
=> “
PEC Option”
=> “
Record
PEC”
. Once ready to begin recording, press the
ENTER
button to begin. Use the arrow button to keep the
guiding star staying at the center of the cross hairs. It takes the worm gear 600 seconds to make one
complete revolution. After 600 seconds PEC will automatically stop recording.
6. If you want to re-record the periodic error, select “
Record PEC
” and repeat the recording
processes again. The previously recorded information will be replaced with the current information.
7. The PE data needs be recorded again if the power is lost.
5.6.3. PEC Data Integrity
This function will check the recorded PEC data integrity.
