Skywatcher FlexTube 12" Dobsonian
Submitted: Wednesday, 1st April 2009 by Duncan Gibb
After much looking around for a new telescope, I settled on the Skywatcher 12” (305mm) dobsonian, I wanted something that had as large an aperture as I could get, but as compact as possible, so here is a quick review of it, for those interested.
The whole thing arrived in two packs, one for the mount, and one for the OTA with all the bits, and its very well packed indeed. Building the mount was really straightforward, while I expected it to be MDF, it has some nice touches, the finish is nice, and the edge binding is of good quality, and doesn’t give the impression it will peel away anytime soon, the general fit and finish is quite nice also. The mount took around 10-15 minutes to build, and fitted together perfectly, with the screwdriver supplied by Skywatcher being just what was needed. The teflon plate that sits underneath is very smooth, and gives a very satisfying “swoosh” sound as its moved about.
The OTA comes collapsed, and has a “shower cap” end on top, and a hard plastic aperture cover for the bucket part of the scope, its simply a case of loosening three bolts, and pulling up on the two large handle on the top of the assembly to extended it into a useable position, it feels quite solid, and gives a satisfying click when locked into position, both up and down.
The finish of the OTA is quite nice also, being a kind of black metallic effect, with what looks like gold flecks through it, I know this sounds garish, but the aesthetics of it, are really quite nice. When collapsed, the OTA shrinks by about a third, I know this isn’t much, but its makes it so much more manageable and easier to lift.
When collapsed the entire thing can be moved around quite easily with the handle on front, and the base has 3 rubber feet underneath, that make it glide along the floor quite nicely, ready to be extended at your place of usage.
So, is it any good? Well the answer to that is “yes” . The OTA balances perfectly on the mount, by means of a round plastic coaster on either side, that kind of floats on two round plastic dowels. As the weight is so well evened out, nudging this around is a snap, and it’s a breeze to keep things centered even at quite high magnifications with just the gently push of a digit. The low centre of gravity helps with movement from the wind etc. and views are always steady, if the balance does go off slightly when viewing near the horizon, of you just want to lock the alt. then the mount has the Skywatcher patented friction bearing thing, which is nothing more than a bearing an washer, that lock against the OTA, without seizing up, or damaging the mount.
The mirror has the usual sparkly circle in the middle of the primary (that always makes me think of the “waiting” cursor in Windows Vista) for collmination, and the secondary has the usually 3 screws for angle adjustment to. Surprisingly, despite being lowered, raised, and moved around, it does hold collimation very well. Star images inside and out of focus are very good, and despite being F5, the coma wasn’t that bad at all, although this will also come down to the other optical components in the chain. Using the standard 25m plossl that came with it, gave nice views, although I use the eyepieces I already have.
So, while in general it’s a good scope, and the optics are of a very good quality, are there any gripes? Well, yes just a couple.
The focuser compliments the mount very well, and looks the part, but it has some issues, it has some sag, and when using the 1.25 adapter, the eyepiece gets set off centre, as there is some play in the size of the adapter, not much, but enough to notice the eyepiece tilt to one side when the grub screw tightens on it. The screws themselves are quite small and fiddly, and never seem to stay locked no matter no tight I make them. There is a screw underneath that’s meant to lock the focuser tube but does nothing much, and I suspect this is one of the things that would need changing.
The finderscope too, while having excellent optics (and I mean excellent) has 3 screws, 2 to align the thing, and one spring loaded “quick release” thing that invariably gets nudged, and needs aligned at the start of every session, something like this should really have been equipped with a right angle finder, as I must look like Elvis Presley doing a limbo dance when trying to look for things higher up than a 45 degree angle.
And lastly, the secondary seems a little small to me (and my calculations) and might not illuminate a 50mm frame, but its only slightly smaller than I would have thought, and doesn’t spoil any viewing pleasure.
In summary, I would recommend this to anyone wanting a large-ish dob, and concerned about the space, while the optical quality isn’t mindblowing, its certainly on the high side of well above average, and this has already provided me with some great views from my backyard of the Sombrero Galaxy, and several other 9th-10th magnitude galaxies close by, not to mention countless DSO’s the fit and finish is very good, and I think it looks very nice to!Article by Duncan Gibb (toryglen-boy). Discuss this article on the IceInSpace Forum.