Celestron, and Meade for that matter, make SCT telescopes with amazing value given the prices. These are mature product ecosystems, meaning that both companies have had about fifty years to "get it right" with both telescopes and myriad accessories. However, there are a few issues I've experienced with my Celestron combo, and I write this in the hope someone at Synta/Celestron is reading this. For reference, I am a very experienced visual observer and a newbie AP'er.
(1) the finder: Celestron currently supplies a straight-through 9 x 50mm finder with it's Edge 8. Use of this requites contortionist skills or a double-jointed neck when the telescope is pointed anywhere near zenith. Further, this finder does not have an illuminated reticle. Celestron makes a perfectly fine 9 x 50mm RACI finder that DOES have an illuminated reticle. Why not supply this instead?
(2) the finder bracket is awful: Celestron uses a proprietary bracket. In place of the usual three adjustment screws, the front ring contains a rubber O-ring that fits over the finder snugly into the ring. On the back ring, only two of the three "screws" are adjustable. This works but is a kluge--what's wrong with the traditional 3-screws on both rings design? Did some fool in times past loosen all the adjustment screws, get poked in the eye, and then sue you, Celestron--your parent company Synta makes perfectly good standard finder mounts? Further, the rings are quite narrow in diameter, so that a standard-tube 50mm finder/guidescope will not fit--one must use Celestron's. C'mon Celestron, how can you be that proprietary ... and that chintzy? Use a dovetail mount and two-ring, six adjustment screw finder bracket like everyone else, please,
(3) the finder bracket/camera bracket clearance: Celestron makes a fine camera bracket that attaches to the OTA tube. However, with certain cameras, there is not enough clearance for the camera body so mounted and the nearby finder. Yeah, one can remove the finder but ... why not make a bracket that provides (or can be adjusted to provide) enough clearance?
(4) 2" visual back: Celeston does not supply a 2" visual back or 2" diagonal with the 8" model. Many of us, including myself, have 2" eyepieces we want to use. One current solution that works great: a Baader Clicklock 2" adapter that screws onto the SCT threads with an aftermarket 2" diagonal. I understand the drive to save money but, really, why limit the scope?
(5) 40mm Plossl: Celestron supplies a modest-quality 40mm Plossl eyepiece with the 8" HD. I'm guessing they do so to emphasize the wide field of the OTA optics. However, this particular Plossl has an AFOV of, I believe, about 43 deg. It is like looking through a soda straw. Why not at least supply something like a 26mm or so Erfle-oid (about the biggest field lens that will fit in a 1.25" holder) that provides greater magnification and roughly the same FOV?
(6) short dovetail: Celestron installs an aluminum Vixen-style dovetail bar on the bottom of the OTA for mounting. For reasons known only to them (perhaps to keep the OTA from sliding off the mount if both mounting bolts are somehow incomprehensibly loosened?), Celestron mounts two knurled-head short bolts, one near each end of the dovetail bar. With the additional weight of either camera equipment or 2" eyepieces, the OTA must be slid forward in the mount all the way to the end of the dovetail bar. Sooo, get rid of the knurled bolt on the mirror end and use the vast sums saved to extend the dovetail another 3/4" or so toward the bottom end: the clearances permit this and it will help in balancing the scope,
(7) Phillips head adjustment screws: I am at a complete loss why Celeston did this: they are difficult to adjust and having a pointy Phillips head screwdriver anywhere near the corrector makes me nervous. I personally like Bob's Knobs because I can feel for them in the dark while collimating on a star w/o fear of scratching the corrector. Others prefer hex-head cap screws because leverage of the Allen wrench handle allows for fine adjustment. Whichever but ... ditch the Phillips head screws, please,
(8) RJ connectors: Celestron uses RJ=style connectors (like landline telephones and ethernet cables use) to attach the hand controller and the Dec cable to the mount connections. These are plastic and flimsy. Please replace them with something like RCA connectors or other robust connectors,
(9) Power supply: Celestron supplies a DC power cord with a male cigarette lighter plug. Most of us do not drive our car to the backyard to plug into the car's cigarette lighter (a bad idea when remote observing lest you car fail to start, BTW, this happened to a friend). Instead, many of us, of course, have a short female plug-and-battery clip cable that allows connection to 12V or many other batteries. Many of us also have AC power at home, for which Celestron sells a rather expensive AC/DC adapter power cable. Either way, I believe the package should be usable out of the box and not require something else,
(10) Weights: Celestron supplies a single 12lb counterweight, which is barely enough for the out-of-the-box configuration. You'll need two counterweights if you use 2" eyepieces or try AP. BTW, some of the usual vendors provide free shipping, which is important for a 12lb object, and some don't,
(11) Mount level: There is no bubble level on the mount. C'mon Celestron! Anyway, you can purchase an aftermarket bubble level for the AVX inexpensively from Starizona,
(12) OAG/Edge 8 compatibility: This is another oversight that simply makes no sense. Celestron makes a wonderful off-axis guider. It is robust, easily adjustable, and has a big prism, the better to find guide stars. It also comes with a number of adapters but ... NOT the one you will need if you want to do AP with your 8" Edge and the x0.7 Celestron reducer. The trouble: the visual back-to-OAG adapter that Celestron supplies is WAY to long to provide the necessary 105mm back focus. The solution: ditch the Celestron adapter and order Part T-01 ("Blue Fireball", call to make sure you get the right one) from Agena. This is thin and provides 105.5mm back focus. BTW, this is a 42mm adapter, meaning it will work with an APS-C size sensor but will vignette a full-frame DSLR. Maybe there is also a 48mm adapter on the same site? But Celestron, why did you manufacture a great OAG but not supply the adapter needed to work with the popular 8" Edge?
(13) Protruding AVX polar alignment knobs: Celestron supplies bolts to adjust altitude and especially azimuth on the AVX. The knobs are unnecessarily long, meaning that when one attempts to carry the mount, they stick into one's midriff, and no, I am not at all obese. This is an easy fix, Celestron,
(14) Polar alignment scope: Celestron's scope is competitively priced and works. It screws into the AVX polar axis and can be adjusted for proper alignment. However, one must loosen the polar scope in it's threads to properly rotate the reticle to the polar constellations, and this badly mess up the alignment due to looseness. What I do is keep it threaded tight and just extrapolate my rotation. Greatness is possible, Celestron, just provide for rotation of the reticle/eyepiece. BTW, a right-angle polar scope would be a whole lot easier on the neck (I observe from 37 deg N latitude).
(15) AVX Dec bearings: please replace the sleeve bearings with ball bearings. Your mounts will have lower RMS tracking errors for AP, you won't need to use that awful thick grease anymore, and you will sell more mounts, and
(16) OTA dust cap: difficult to get on. Yeah, after awhile I discovered those matching bumps: one on the OTA and the other on the cover. Consider painting them white for nighttime visibility.
OK, enough beating up Celestron. Here are some of the things I really like about the combo:
--focuser: OK, f/10 is pretty tolerant but the focuser is smooth and with adequate pitch control. Feathertouch it ain't but ... it works very well,
--hand controller: aside from the connectors, this is a wonderful unit and I love using it. BTW, could you please allow substitution for all those weird Arabic-derivative star names--many of which are obscure--and use Bayer designations (e.g. Dubhe = alpha UMa, etc.) so that we might know which constellations our prospective alignment and calibration stars are in?
--goto precision: after even a cursory polar alignment with the polar alignment scope, "2 star alignment," followed with two calibration stars, the object of my lust is centered within a 10mm eyepiece, always. Nice!
--optical quality: mine are adequate but not great, about lambda/5.5 end-to-end wavefront P-V at 0.5um by careful star test, mostly due to an intermediate zone. Still, given the complexity of the optics train and the price, I am really impressed!
--build quality and quality control: so far, everything worked out of the box and continues to work. Great!
--OTA handle: a stroke of genius from Celestron here--the handle on the mirror end makes carrying the OTA super easy!
--OTA light weight and compactness, given the 8: SCT. Isn't this a big reason we buy SCTs and buy Celestron?
--AVX mount head lightness. Very stable for it's low weight. Maybe I got lucky but I have been using it and the 8" Edge OTA successfully for AP with < 2 min exposures, which is all my light-polluted skies will allow anyway. 'Easy to carry out of the garage to the backyard, even with the tripod attached (I am a healthy adult male), and
--the Edge 8" carrying case: well-made and quite wonderful. Holds the OTA safely & securely, and comes with an internal zippered pouch for accessories.
So, Celestron, you've got the really important factors right: solid and stable goto mount, great portability for the size, and decent optics. A bit of work with your accessories and you will have a truly astonishing product!
Happy observing always,
Edited by dhferguson, 02 June 2020 - 07:27 PM.