Amen to what Michael has said. The main advantage of the first telescope is that it is a fork and you can view objects in the north more readily but the stability issue goes with the German equatorial. The same mount holds much larger telescopes (see Celestron's website) so it should be stable for an 8". I have the mount the CG-5 was based on, the Vixen GP-DX, and it holds an 8" very well and a 9.25" well enough to due planetary imaging. Clear Skies Don -----Original Message----- From: utah-astronomy-bounces+djcolton=piol.com@mailman.xmission.com [mailto:utah-astronomy-bounces+djcolton=piol.com@mailman.xmission.com] On Behalf Of Michael Carnes Sent: Thursday, March 23, 2006 6:23 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] Trying to decide between two telescopes On Mar 22, 2006, at 10:00 PM, Chris Russell wrote:
I love my telescope except for the fact that I have to decide between it or the kids if I'm going somewhere. Sounds perfect just the way it is.
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'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. 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. Hope this is helpful, Michael
I've decided that an 8" Schmidt-Cassegrain is just the ticket and I think I've narrowed it down to these two models which are in my price range and appear to have all the features I want:
Option #1: Celestron Nexstar 8i Product Information: http://www.celestron.com/prod_pgs/tel/nx8ise.htm
Option #2: Celestron C8-SGT Product Information: http://www.celestron.com/prod_pgs/tel/c8sgt.htm
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