Post by Chicago Astronomer - Astro Joe on Feb 7, 2015 14:30:51 GMT -6
I received this nice email from a new C11HD owner who has a issue with the corrector plate...
Hello Joe,
I've posted on a couple of forums, but no answers yet. I figured it would be appropriate to ask THE native Chicago astronomer for expertise.
I purchased a used C11 HD and received it last night. Everything seems to be in good shape, a bit dusty, but good. I haven't looked through it yet, but I immediately noticed that the corrector glass is pretty loose and rotates easily when trying to remove the fastar secondary. Is this normal? How is collimation supposed to hold like that?
I didn't attempt to remove the fastar secondary for fear of causing damage to the corrector glass. Just wondering if other edge hd owners have experienced something similar, if it's normal or easily corrected, or if it warrants me having to return this.
Searching through Google for answers I came across this amazing post of yours, Chicago Astronomer C11 Disassembly) and I figured I'd ask!
Thanks!
Gabe
Hi Gabe,
The C11 is a great instrument, (HD or other), and congrats on obtaining one.
It will display the wonders of the cosmos beautifully with all that aperture and still portable enough.
The corrector plate should not freely spin under the hold down ring...but not a reason to return the scope. But when the Corrector plate spins out of it's set position, the proper collimation has been lost. For best optimum viewing, the corrector plate, the secondary housing and the primary mirror should be in factory pre-sets. Getting it back to proper alignment is not a difficult project, but it does take time and patience.
Along the edge of the corrector plate is a serial number and that corresponds to the focuser knob on the primary. You can spin the corrector plate till the digits line up with the knob...which in my scope is roughly at the 4/5 O'clock position. There, it should be roughly set and aligned.
Unless the secondary housing has also spun around, it should also be in alignment with the corrector plate. (There is usually a small line or indicator along the outside ring of the secondary.) Digits, line and knob all in line.
Corrector plates are tough and hardy...and will take a cleaning nicely.
...might as well.
Let me know on your C11 adventures.
Chicago Astronomer Joe
I've posted on a couple of forums, but no answers yet. I figured it would be appropriate to ask THE native Chicago astronomer for expertise.
I purchased a used C11 HD and received it last night. Everything seems to be in good shape, a bit dusty, but good. I haven't looked through it yet, but I immediately noticed that the corrector glass is pretty loose and rotates easily when trying to remove the fastar secondary. Is this normal? How is collimation supposed to hold like that?
I didn't attempt to remove the fastar secondary for fear of causing damage to the corrector glass. Just wondering if other edge hd owners have experienced something similar, if it's normal or easily corrected, or if it warrants me having to return this.
Searching through Google for answers I came across this amazing post of yours, Chicago Astronomer C11 Disassembly) and I figured I'd ask!
Thanks!
Gabe
Hi Gabe,
The C11 is a great instrument, (HD or other), and congrats on obtaining one.
It will display the wonders of the cosmos beautifully with all that aperture and still portable enough.
The corrector plate should not freely spin under the hold down ring...but not a reason to return the scope. But when the Corrector plate spins out of it's set position, the proper collimation has been lost. For best optimum viewing, the corrector plate, the secondary housing and the primary mirror should be in factory pre-sets. Getting it back to proper alignment is not a difficult project, but it does take time and patience.
Along the edge of the corrector plate is a serial number and that corresponds to the focuser knob on the primary. You can spin the corrector plate till the digits line up with the knob...which in my scope is roughly at the 4/5 O'clock position. There, it should be roughly set and aligned.
Unless the secondary housing has also spun around, it should also be in alignment with the corrector plate. (There is usually a small line or indicator along the outside ring of the secondary.) Digits, line and knob all in line.
Corrector plates are tough and hardy...and will take a cleaning nicely.
...might as well.
Let me know on your C11 adventures.
Chicago Astronomer Joe