Celestron Ultima 11 - Page 41

Ultima 9
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and Ultima 11 Manual 41
4. Take a few minutes to practice guiding. This will help you familiarize yourself with the periodic error of
the drive and the operation of the hand control box.
5. Press the “PEC” button once to activate the record (REC) mode. The LED below the word “REC” will
illuminate indicating that the record mode is working.
NOTE: The star should stay centered on the cross hairs for a few seconds without using the hand controller before
activating the PEC function.
1. Guide for at least four minutes.
2. Try not to overshoot corrections in right ascension
• Ignore drift in declination
• Activate the playback function by pressing the ‘PEC’ button once. All corrections made during the record
mode will playback in a cycle that lasts four minutes.
3. Point the telescope at the object you want to photograph and you are ready to begin.
If you record for more than four minutes, the system will play back the corrections made during the first four minutes
and continue to add new corrections as long as the ‘REC’ function is activated. Thus, you can technically guide a
photo while in the ‘REC’ mode. However, if a non-periodic error appears you will have to guide it out manually
twice; once when it first appears, and a second time four minutes later when the system plays back the corrections.
NOTE: The focus buttons and the fast slew functions are locked while the PEC function is activated. This
eliminates the possibility of shifting the focus or moving the telescope suddenly during an exposure.
Once you have used the PEC function for a while you may mistake its operation for the way the drive normally
operates. The best way to see how well the PEC function works is to turn it off. PEC results improve with practice
and patience.
Does the PEC function make unguided astrophotography possible? Yes and no. For solar (filtered), lunar, and
piggyback (up to 200mm), the answer is yes. However, even with PEC, off-axis guiding is still mandatory for long
exposure, deep sky astrophotography. The Reducer/Corrector lens reduces exposure times making the task of
guiding a little easier. More on each of these forms of astrophotography in the section on ‘Celestial Photography.’