NorthernLight
23-11-2014, 03:45 PM
Hi There,
I am hoping that someone has the time to read through my short report and can point me in the right direction. I have read pretty much all forum entries and the suggested links like Astrobabys guide to collimation.
With my Celestron 6"/F5 Netwon I have not had the same issues.
Please Help! I`d be glad for any helpful advice.
After cleaning both mirrors of my GSO 12"/F5 Netwon (Dobson mounted) I have re-assembled all parts but cannot get the secondary`s position right.
I use a laser and a pinhole. This is what I did so far:
1) I bring the secondary to the right height, so I see it as a circle through the focuser.
2) I adjust the secondaries tilt so that the main mirrors reflection appears centered in the field of view.
What I observe is that the quadrants that are formed by the spider vanes are not symetrical. The lower left quadrant is the largest, the top right one the smallest. I can do whatever I want, no change in tilt or height adjustment centers the view and brings all quadrants to the same size.
I also observe that the center spot on the primary is not aligning with the center of the focuser drawtube (my pinhole).
A member of my local astro club recommended using a laser for the secondary alignment. This is the procedure:
I) insert collimation laser (Orion LaserMate Deluxe) into focuser drawtube.
II) adjust secondary until the laser beam is centered in the primaries center spot.
When I then use the pinhole again, I cannot see the full disc of the primary through it. It is somewhat shifted to the lower left.
I dis- and re-assembled the whole system twice but faced the same issues. It appears as if the focuser drawtube, if it were extended, does not meet the center of the telescope tube.
I know it all sounds a bit confusing, if not bizarre. But I really need some help here. Even if that is an address to some shop that can fix matters.
Many Thanks
I am hoping that someone has the time to read through my short report and can point me in the right direction. I have read pretty much all forum entries and the suggested links like Astrobabys guide to collimation.
With my Celestron 6"/F5 Netwon I have not had the same issues.
Please Help! I`d be glad for any helpful advice.
After cleaning both mirrors of my GSO 12"/F5 Netwon (Dobson mounted) I have re-assembled all parts but cannot get the secondary`s position right.
I use a laser and a pinhole. This is what I did so far:
1) I bring the secondary to the right height, so I see it as a circle through the focuser.
2) I adjust the secondaries tilt so that the main mirrors reflection appears centered in the field of view.
What I observe is that the quadrants that are formed by the spider vanes are not symetrical. The lower left quadrant is the largest, the top right one the smallest. I can do whatever I want, no change in tilt or height adjustment centers the view and brings all quadrants to the same size.
I also observe that the center spot on the primary is not aligning with the center of the focuser drawtube (my pinhole).
A member of my local astro club recommended using a laser for the secondary alignment. This is the procedure:
I) insert collimation laser (Orion LaserMate Deluxe) into focuser drawtube.
II) adjust secondary until the laser beam is centered in the primaries center spot.
When I then use the pinhole again, I cannot see the full disc of the primary through it. It is somewhat shifted to the lower left.
I dis- and re-assembled the whole system twice but faced the same issues. It appears as if the focuser drawtube, if it were extended, does not meet the center of the telescope tube.
I know it all sounds a bit confusing, if not bizarre. But I really need some help here. Even if that is an address to some shop that can fix matters.
Many Thanks