Yesterday afternoon I aligned the polar scope reticle in vertical and horizontal direction towards a distant buidling because the night before I suspected that it’s not aligned well anymore. I was right!
I’m not sure if this is my mistake. Before that all started, I transported the mount with attached counter weights from my balcony back to my apartment. The gear locks were disengaged, but I’m not 100% sure if I forgot the allen wrench in the RA-axis blocking hole. Maybe due to the swinging of the counterweights something happened…
The RA axis was twisted clockwise a bit when I aligned the reticle horizontal and vertical. (see image to the right)
But much more likely it was the polar scope that was twisted counter clockwise…
I contacted iOptron support including this photo to the right. The iOptron support is really great. They responded on a Saturday in less than one hour with a solution!
They send me this instruction manual:
https://www.ioptron.com/v/Support/CGEM2x_iPolar_Replacement.pdf
I had to loosen the whole polar scope and of course after I aligned the scopes reticle in vertical and horizontal position, the scopes axis was not aligned with the RA axis anymore. It was a desaster…
So after fixing one problem, there was a new one.
Now I also had to calibrate the polar scopes axis back to center…
Aligning Reticle
For the aligning process it is necessary to remove the red RA rear cover.
The 2 red circled screws are for mounting the scope itself. I needed to loosen them to rotate the scope to align the reticle horizontal/vertical.
The green circled screw (there are two more screws not visible on the image) is to fine adjust the alignment of the scopes axis with the RA axis.
I never before calibrated a polar scope… on my Star Adventurer it never was necessary.
So I started to adjust the screws on the eyepiece. Unfortunately I didn’t know about the third bottom screw on the eyepiece, so I failed at every adjustment with only 2 eyepiece screws… after a short google search I found help:
Lesson learned
It’s impossible to align the polar scopes axis to the RA axis only with two eyepiece screws. I’ve to use also the altitude and azimuth ajdustment screws for calibration (maybe the calibration can be done without alt/az screws, if one is using all 3 eyepiece screws… I’ve to check this)!
Polar Scope Calibration
During daylight, spot to a building edge or church tower or a tree and align the reticle on it. Now turn the RA axis. The center of the reticle has to stay on the same point, if not, the polar scopes axis is not parallel to the RA axis anymore.
In that case the polar scope has to be calibrated.
The fun begins…
First I rotated the RA axis 90° counter clockwise and centered the reticle by adjusting the alt./az. screws. Then I rotated the RA axis 180°. The center of the reticle has moved to top right.
RA turned 90° CCW from initial position 
RA turned 180° CW –> needs calibration!
Next I divided the reticle’s center path in two parts. One part is corrected with the eyepiece screws (red arrrow), the other part is corrected with the alt./az. screws (green arrow).
Reticle’s center path 
Red = Eyepiece screws, Green = Alt/Az screws
Then the same again: center reticle, turn 180°, divide the (hopefully shorter and shorter) path in two parts, calibrate one part with the eyepices screws the other with the alt./az. screws.
After many corrections 
RA turned 180° CW –> calibrated
More than one hour later I managed to calibrate the polar scope and the reticle is now perfectly aligned horizonal/vertical too! What an adventure 😉
So far, it seems everything went fine 🙂
At least I photographed this image after the calibration with only 7% unusable lights due to slight DEC trails (9 out of 134 lights)!
The polar scope seems to work after calibration 🙂
