Thank you for a really lucid explanation, Patrick -- things I wish I had known back then. (And to think my son is teaching a lab next semester on optics! I should have known better than just take the telescope apart and put it back together any old way.) How can we as a group keep track of information like this? Any way to set up an electronic filing system that could help the neophyte? My next question is, but what can I do now since I never marked the corrector in the first place? Is there any way to figure how to orient it long after the fact? Best wishes, Joe
Joe Bauman wrote:
Very interesting and informative, Patrick. What I'm wondering is, when you put the corrector plate back on, does it have to be aligned any particular way to the mirror? From what I've been able to find on the web it only needs to be "close". They
defined that as being within about 20% of the original position. However, it's a simple matter to get it very close by simply marking the corrector and the tube. I've used both magic markers and masking tape in the past.
One should use caution when pulling the corrector away from the tube. Every S/C (C-5, C-8 & C-14) I've pulled the corrector off of had three tiny spacers positioned at about 120 degree intervals around the circumference. I understand they do need to go back where you found them.
Accomplishing that is no big deal though. You can see them once the corrector's retaining ring has been removed and before the corrector itself is removed. That being the case, one just marks their location with a permanent marker on both the corrector and the inside of the tube (technically one really only needs to mark the corrector *OR* the tube but I mark both just to be sure).
That is, is there a 12 o'clock that has to line up with an equivalent 12 o'clock on the mirror? I could find no mention of the mirror/corrector relationship on the web. But as long as all one is doing is removing the corrector for cleaning the above procedure will work fine.
If the primary mirror is coming out there should be no problem as long as it's left fixed to is back plate since there's only one way to put it back in (Mr. Murphy's laws not withstanding <grin>).
However, if the primary is removed from it's back plate then I'd suggest doing as I did and mark the mirror and back plate before removing the mirror from the plate. That way you'll know exactly how to put it back together.
To be honest, if I knew then what I know now I might not have pulled the mirror off the back plate. I did that thinking drilling the holes in the central tube would be difficult and I did not want to mess up the mirror. However, drilling and tapping the holes turned out to be very easy and, in hindsight, could have been done with the mirror left on the back plate (though with its front surface protected by tissue paper and a cardboard cover).
Bottom line, for me the worst part of taking it apart was my fear that I'd run into all kinds of trouble. As it turns out my fears appear to have been unfounded. It was very easy to take apart and the reassembly, to this point at least, has been equally easy.
Patrick
_______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com