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imjeffp
Senior Space Cadet
Reged: 09/30/03
Posts: 4427
Loc: Cedar Park, Texas
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I've been window shopping for an 8" SCT, so I thought I'd ask around. Mount differences aside, is ther a real difference between an AS C8-SGT, NexStar 8i, NexStar 8GPS and CGE 800?
And speaking of mounts: Fork-mount on a wedge or GEM?
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Blog
ST80 • AT80EDT/LXD650
ETX-90/DS-2000 • 10" LX200 Classic ("The Quarter-Meter Telescope at the Heritage Park Observatory")
SPC900NC • DMK21AF04 • Digital Rebel XT
  
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jrcrilly
Refractor wienie again
Reged: 04/30/03
Posts: 22464
Loc: NE Ohio
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You've asked an easy one and a hard one there.
There are subtle differences between the OTA's used in the different models you mention, but all have the same primary mirror and focuser so all should be about equal optically. The CGE800 and Nexstar 8GPS use a carbon fiber optical tube and have a removable secondary mirror for Fastar use. The N8i has neither feature and I'm pretty sure the C8-SGT doesn't either. The N8i version also seems to have fewer mounting holes on the front & rear cells for accessories. Most users will never see any difference from these changes (I know I wouldn't) but they are there.
Forks v. GEM is more complex question. For ease of setup (plop it onto the tripod, align, and begin viewing) the forks win in a big way. The GEMs generally break down into lighter components (although I suspect the CGE mount weighs more than the entire N8i). The GEM will tend to put the EP in more awkward positions but leave all the room you could ever want behind the focuser for imaging hardware, while the forkmounts have limited clearance either at azimuth (no wedge) or pointed North (on a wedge). I'm using a forkmount in the observatory and a GEM for my portable setup - but that could change any time...
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John C
Urban Observatory
Tele Vue Pronto
A&M/Astreya 76mm F/6 APO
TMB/LOMO 80mm F/7.5 APO
Tak FSQ-106N F/5 APO
Meade 152ED F/9 "APO"
152mm F/10 achromat
Tak CN-212 8" F/12 classical Cass/ F/4 Newt
Teeter 20" F/3.8 truss Newt w/ServoCat
LXD750, EM-200, CI-700
ST-10XME
Edited by jrcrilly (10/29/03 06:41 PM)
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imjeffp
Senior Space Cadet
Reged: 09/30/03
Posts: 4427
Loc: Cedar Park, Texas
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[quote] I'm using a forkmount in the observatory and a GEM for my portable setup [/quote]
Isn't that backwards? Seems to me the observatory would be an "align once" sort of affair...
Assuming I want to spring for goto, the Meades seem to have the upper hand in the software. I suspect this is like a PC/Mac question, but which is "better?"
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Blog
ST80 • AT80EDT/LXD650
ETX-90/DS-2000 • 10" LX200 Classic ("The Quarter-Meter Telescope at the Heritage Park Observatory")
SPC900NC • DMK21AF04 • Digital Rebel XT
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jrcrilly
Refractor wienie again
Reged: 04/30/03
Posts: 22464
Loc: NE Ohio
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[quote] . [quote] I'm using a forkmount in the observatory and a GEM for my portable setup [/quote]
Isn't that backwards? Seems to me the observatory would be an "align once" sort of affair...[/quote]
Yes, it's subject to change. The GEM was in the observatory until the large forkmount showed up. It's just too heavy for portable use so it wound up in there.
The good news is that modern GEMs set up quickly & easily and a polar alignment close enough for extended, high magnification visual use takes only a couple of minutes.
The Blue v. the Gray discussion will sound much like Ford v. Chevy. I've owned and use both M & C forkmounts and GEMs and have found things I like about all of 'em. The nicest 8" SCT I ever owned for portable use was a NX8GPS; amazing goto & tracking accuracy, lightweight, rock-solid mount, great optics. I do feel the Autostar II controller is more capable, though. HCAnywhere gives the C's some very impressive bells & whistles but I don't use a laptop in the field so it wouldn't benefit me.
In the lighter GEMs I've owned a number of LXD55's and have always received good performance from them but I'd lean toward the Celestron version today for the much better tripod and for what I hope will be a more reliable motor package. In the heavier GEMs I like the CGE a great deal. The big Meade GEMs are very old technology and still quite expensive.
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John C
Urban Observatory
Tele Vue Pronto
A&M/Astreya 76mm F/6 APO
TMB/LOMO 80mm F/7.5 APO
Tak FSQ-106N F/5 APO
Meade 152ED F/9 "APO"
152mm F/10 achromat
Tak CN-212 8" F/12 classical Cass/ F/4 Newt
Teeter 20" F/3.8 truss Newt w/ServoCat
LXD750, EM-200, CI-700
ST-10XME
Edited by jrcrilly (10/30/03 07:15 AM)
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Anonymous
Unregistered
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I changed my Vixen GP mount (I bought a GP-C8) for a Takahashi EM200 and have never regretted it. Buy the best mount you can,
particulalry if you wish to do any imaging with a long focal langth telescope such as a C8 without Fastar or a focal reducer.
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