As I mentioned in my last post, I was less than impressed with the views through my recently built telescope. I was blown away by the views of DSO’s (Deep Sky Objects) such as nebulas and galaxies, but when I pointed the scope at Jupiter I saw nothing more than a mushy blob with two lines through it (the northern and southern equatorial bands). Jupiter looks much sharper in my 90mm APO (Astro-tech AT90EDT) than it does in my 333mm newtonian! A star test revealed that the mirror was overcorrected. This is not surprising since Coulter wasn’t exactly known for their precision optics.
So what am I going to do about this? Fix it, of course! But before I take a pitch lap to the 13.1″ f/4.5 mirror I should probably know what I’m doing. All of the advice points that starting one’s mirror making career is best done with a 6″ f/8 or 8″ f/6. Since I have 2 6″ pyrex blanks, I’ll start with a 6″ f/8. I have been accumulating all of the books, mirror blanks, and mirror test equipment that I could get my hands on over the past few months. I recently built myself a foucault tester based on the Stellafane design. I used it for the first time last night to test my 13.1″ mirror (as well as a 10″ meade DS-10 mirror that I found on craigslist for $75!).
All that’s left for me to do is to build a grinding stand, which I’m planning on doing today. I hope to update the blog more frequently rather than I have been.