Celestron Nexstar 102 GT
Posted 07 January 2013 - 09:19 PM
Posted 07 January 2013 - 09:52 PM
Posted 08 January 2013 - 09:56 AM
Posted 08 January 2013 - 12:18 PM
Posted 08 January 2013 - 02:34 PM
Yes but I had to get a different bolt from the hardware store to make it work.
Does the mount directly attach to the HAL tripod?
Posted 16 January 2013 - 03:29 PM
I have much bigger telescopes, but I love this one because it is so portable and useable. (And for what it is worth I prefer the focuser on this one to what I have on my Celestron C6-RGT).
Posted 17 January 2013 - 12:34 PM
Posted 21 January 2013 - 07:45 PM
Build quality – overall good:
Sturdy, smooth rack & pinion all-metal focuser , with accessory shoe.
Plastic lens cell and especially too short plastic dew shield - dew shield protects lens, but doesn't extend very far in front (I estimate only 3 inches ahead of objective) for proper dew control.
Dovetail bar bolted to tube is metal, but too short for much back and forth balance adjustment (2”-inch diagonal + 2-inch eyepiece require a little weight added at objective to balance with the stock dovetail).
Tube weight is about the same as my older 80mm f/6 Nighthawk with heavy clamshell and dovetail, but the C-102 gives twice as long of a moment arm. While the smaller scope is solid on a Porta-mount, the C-102 feels closer to upper limit for same mount. It works fine with a little care not to bump, awareness of damping time.
Optics – nice!
Star pattern symmetrical and consistent inside and outside focus. CA was noticeably less than seen in my Nighthawk 80mm f/6. Moon has only slightest fringe at limb, no color on axis. No sign of pinched optics.
Holds power well; could have gone over 160x on moon. Lunar view help up very well at 160x. It helped that the view was stunning, with terminator sunlight just illuminating the higher side of the straight wall, and a small crater poking above the straight wall’s shadow. Under higher sun, details inside Atlas and Hercules were clear.
M-42 had a lot of wispy detail under 1st quarter moonlight, with a field of 1.5 degrees giving crisp star images as the overall impression. Sirius was awash in blue but Jupiter’s narrow blue halo was less noticeable and detail seen a little better than in Nighthawk, Jupiter still a bit of a challenge w/o any filter due to CA, but less so than in the faster short tube.
This is a very nice lunar scope. It will complement the Nighthawk for deep sky reach and higher power detail, trading off the wider views and air portability of the smaller f/6 scope.
I find Jupiter a tough object for false color compared to the moon, or the somewhat monochromatic (at least compared to Jupiter) Saturn and Mars. I'm looking forward to more deep sky use when the sky is darker.
Porta or similar alt-az would be very adequate, but I plan to make some tube rings (padded pipe hangers or hose clamps – in the frugal spirit of $120 OTA) to use this on a Russian TAL-1 GEM. I’ll work on a dew shield extension too. Others could add rings and a longer dovetail for easier balance on Vixen type mounts.
Overall a good buy for someone who has diagonals and eyepieces. The OTA is also offered with 2” diagonal, or 1.25-inch diagonal and 2 eyepieces, for about $40-$50 more than the bare OTA with only 2”-1.25” adapter that I got.
Need a finder? The Celestron StarPointer red-dot has adjustable brightness and is only $14.95 on sale through January. I may get a 2nd one of these. Compared to the ‘giant mars eye’ from old Apogee and Stellarvue, the Celestron has a smaller and slightly darker window that still works well under the stars. The Celestron red dot is a maybe 2 minute of arc disk; this seems easier to pick up instantly compared to the pinpoint dot of the giant mars eye. While the Rigel Quikfinder remains my favorite RDF, this simple red dot works wells and comes with 2 mounting plates.
Posted 22 January 2013 - 06:31 AM
Thanks for the review. I do have one question. Does the accessory shoe fit the Synta/Orion style finder mount?
If I hadn't just got a Vixen A80Mf I would order a 102 GT OTA.
(Must resist.... Must resist.... Must resist.)
Posted 22 January 2013 - 11:54 AM
I got the GT for 2 reasons. First, to add a little more high magnification grab and go capability for the PortaMount for backyard looks at events like the moon and Jupiter last night. Second, to have a scope largely dedicated to the used TAL mount that I like for its "old school" operation. The TAL is too light for my C-8 and too tall for a small Newt with kids, and while I made an adapter for the Nighthawk and used the slow motion for manual tracking, that combination always seems like overkill unless at a star party. The 102 is a good match, about like the various 80 to 102mm Omni mount combinations.
The 102, like a longer f/ratio (less CA) 80mm, is also a little more satisfying lunar and double star scope than the 80 f/6. I tried a C-90 for several years, it was fun but never really exceeded the Nighthawk enough for my higher power use, did less well on deep sky, but was lighter in weight. Overall the C-90 was less versatile for anything but lunar grab and go, and that was hard to call, the edge only for less CA in the C-90. I think 80 and 102 f/10 or f/11 is a lot more apples and apples subtle difference than 80f/6 and 102 f/10. For years a sketcher on CN regularly posted observations from his 'planet hunter' 80 f/11.
Having said all that, the 102GT seems like a really good deal for $120 with caveats listed before about the plastic lens cell (which seems OK on my example) that holds nice optics, short mount doevetail, no rings or finder, etc., and somewhat skimpy plastic dewshield.
To answer your finder shoe quaetion: the 102 GT focuser is probably a Synta, given Celestron's ownership by Synta. It looks the same as my old Nighthawk focuser too. I once had a Vixen small Newtonian OTA and the dovetail shoe for that finder needed filing to swap in the narrower Nighthawk focuser dovetail, and I think the Nighthawk used a cleaned-up Synta focuser in the old days. So Vixen finder dovetails may be a little wider 'wedge' than Synta (and I think Synta are same as Celestron).
Posted 22 January 2013 - 12:20 PM
The Orion finder mount fits the Vixen OK, and I would think it would fit the Celestron as well.
Like you I don't think there is enough difference between these two scopes for me to warrant purchasing the 102. The CFO already says I have too much stuff taking up space in the house. Its just that I have a hard time resisting a good bargain!
Posted 22 January 2013 - 02:15 PM
Posted 22 January 2013 - 02:19 PM
Posted 12 April 2013 - 01:41 PM