Michael Carnes wrote:
But if you must change, I'd recommend the SGT version of the scope. As a German equatorial, It might take a few extra minutes to align. But it will be considerably more stable. I have the first generation of Nexstar 8". I understand they've improved it considerably, but my experience tells me that still isn't enough. The single fork arm just doesn't have enough mechanical stability and high magnification views are seriously compromised because of periodic error and damping problems. From what I hear, the CG5 mount in the SGT version has been beefed up, and while not observatory class, it can still hold the 8" nicely. By the way, my criticism of the Nexstar only applies to the mount. The OTA is very nice. Someday when both time and money allow, I'll mount it appropriately.
I was wondering if the single fork could really be all that steady, so I appreciate your feedback. I understand it's easier to use and set up, but I would definitely prefer something more steady.
I'm sure you're already aware of this, but the views you get with an 8" SCT will be considerably different from a 12.5" Dob. In addition to the full magnitude difference in light-gathering, your field of view will change a lot. Planetary and lunar views are superb with an SCT (refractor purists will disagree, but they've got to justify dropping $3,000 for 4 inches of aperture). Other views that you've grown used to (let's say M51) will lose considerable detail.
Yes, I realize this probably wouldn't replace my other telescope if I wanted the best view. I would just like to get something that would work well as a pinch hitter if I'm taking my kids along while traveling somewhere (such as camping or visiting relatives in Southern Utah). Also, I have the crazy idea of trying some photography, perhaps using picture stacking software, though that's really not much of a priority in trying to make my decision.
One last thing. If you pop for either of the scopes, be sure to spend an extra $15 on a set of Bob's Knobs. These are little thumbscrews that replace the collimating screws on the scope. Depending of Celestron's mood, they give you either phillips head or hex head collimating screws. To collimate, you have to stand in front of the scope, just hoping you don't scratch your corrector. And you've got to keep track of the tool. With Bob's knobs, you can easily reach the adjusters while at the eyepiece. Collimation changes from a chore to a piece of cake.
Thanks for the advice. That sounds like an excellent idea. -- --Chris Russell