At this fast of f-ratio the collimation becomes extremely important (I have a 13.1" f/4.5 Dob and I've learned this in a hurry) for planetary viewing. Also, a fast reflector tends to develop "coma" where the stars toward the edge of the field of view become elongated, especially in wide field eyepieces - this is a problem that has to do with the nature of parabolic mirrors. Televue makes "Paracorr" which corrects this parabolic abberation, for just under $300. As far as eyepieces, if you have a drive on your mount, you might want to look at orthoscopics for a smaller field of view on planets, the Monocentrics reviews are good but they are pricey eyepieces. I use a 4mm Radian or a 7mm Siebert/Barlow combination for planetary viewing, they don't give as good a view of Mars as my 8" f/6 Dob did or my 70mm Orion refractor does, I'm still working on perfecting my collimating technique on the 13.1". For DSO and star viewing I use wide angle eyepieces and notice the coma, but I can live with it for now as the views are so spetacular.

• F/4 Collimation - gjeckes - October 30, 2003 - 19:09 UTC
  • F/4 Collimation - jkoptic - October 30, 2003 - 20:36 UTC
    • F/4 Collimation - gjeckes - October 31, 2003 - 04:18 UTC
      • Pictures - jkoptic - October 31, 2003 - 04:44 UTC
        • Pictures - gjeckes - October 31, 2003 - 05:10 UTC
          • Pictures - jkoptic - October 31, 2003 - 16:33 UTC
            • Pictures - gjeckes - November 1, 2003 - 01:02 UTC
            • Pictures - gjeckes - November 1, 2003 - 07:07 UTC
              • Pictures - jkoptic - November 2, 2003 - 05:23 UTC
                • Pictures - gjeckes - November 2, 2003 - 08:06 UTC
                  • Secondary offset - jkoptic - November 2, 2003 - 18:30 UTC
                    • Secondary offset - gjeckes - November 2, 2003 - 21:41 UTC