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16" Goto Dob - first light.
Warning - long and tedious post follows.
Last Monday afternoon saw the receipt of my new 16" Skywatcher Goto dob from AstroPete's in Brisbane, and I thought I'd share a few initial thoughts for anyone considering purchasing this instrument. It arrived in 3 boxes: one (comparatively) small and reasonably heavy box containing the primary mirror, a second quite large but still manageable box housing the OTA, and a third large box housing the base and side panels whose weight was comparable with that of a small automobile laden with bricks. Definitely a two man lift for this, which certainly had me concerned about the general mobility of the unit once assembled. In the course of my online research prior to purchasing it, I was very much aware of the sheer size of this scope, and the magnitude and weight of the boxes it arrived in certainly did nothing to dispel these concerns. I would also comment that if you think summertime in Brisbane is an ideal period during which to be moving large telescope components, you err badly.
The various bits and bobs were very securely packed in foam/cardboard, and even double boxed. The materials are melamine board with plastic edging - pretty standard fare for anyone familiar with the skywatcher range, and with care should hopefully last many years. Having previously assembled a similar 8" scope it was fairly straight forward to bang this together, although the fixings are slightly different to allow quick disassembly. At a leisurely pace interspersed with trying to work around a mountain of cardboard and occasional time-outs for tennis updates, it took a little under 90 minutes to have the whole thing assembled, by which time sweat was spurting from every pore in a quite unseemly manner. The base goes together easily, and probably the hardest (but still not hard) part was placing the primary into the cell and back onto the OTA. Once assembled, it really is a behemoth of a telescope. I'm 6' tall and need a small step to see into the eyepiece when the scope is anywhere near zenith.
On my 8" goto, any possibility to disengage the motor drive is hidden inside the motor casings (not even sure if there is this option - never pulled it apart), making manual slewing very awkward. I was pleasantly surprised that the 16" has external hand wheels on both motor drives that easily disengage the motor, and once done it moves effortlessly at a very gentle touch. Itching to try it out, I then had to disassemble it all, move it outside, and assemble it again, which takes about 10 minutes - generally not something you want to do too many times in one night. Moving the actual components is a task in itself - there in not a chance in hell of moving the scope in one piece on your own. The OTA needs to be removed (pretty heavy, but not impossible to lug over short distances), and the base needs all the panels removed - no one with any respect for their back would attempt to lift it by the handles. The base itself is more than 800mm in diameter and I found the easiest way to move it is to roll it - I've since devised a long ring of carpet offcut that I wrap around it to protect the plastic edging. Handling the OTA has also prompted me to get a trolley with some straps for storage and transport - moving it any distance by hand is going to get tiresome pretty quickly as it's quite heavy - significantly heavier than my 8" all in one piece.
Set up next to my 8" dob, and nestled between carport, house and tall trees, all I could really try out was Orion, which was directly overhead. There is a fair bit of light pollution near me so I'm assuming the greater light grab of the 16" would also magnify the LP, but the difference was quite marked - the nebulosity definitely extended further, seemed to have more detail (perhaps even slightly differing colours, although I may be getting carried away here), and was significantly brighter with the 16". The hand controller, unlike earlier versions, doesn't have a dedicated power supply: previously you could plug it into power with the supplied power cord, connect it to your pc, and update the firmware. Lacking the dedicated power socket, you need to either have the telescope powered up and bring the laptop to the telescope, or bring the side panel with the altitude motor and power input socket to your pc, which seems a little cumbersome.
Last night I ventured to a dark site for its maiden voyage. Getting it on and off the ute and set up was less hassle than I anticipated, and by dusk was ready to rumble. Turning on the unit gave me a message to the effect that it couldn't recognise either of the axis motors, but a few on-off switchings and a healthy dose of profane language had this sorted - apparently this is not uncommon but I'll be investigating further as this is not really acceptable. Anyway, collimation was easily done and the 2 star alignment process is pretty straight forward for anyone familiar with these machines, so I was off and running in short order. I aimed for a lot of the standard favourites: orion nebula, carina nebula, 47 tuc, tarantula nebula, etc, and was blown away by the brightness compared to the 8" scope. 47 Tuc and the carina nebula were the real standouts, and while I'd never been into planetary nebulas before, it easily picked up the blue planetary, eight burst planetary, and (to a lesser extent) the crab nebula. The sculptor galaxy was easily distinguished, although I was looking before it was fully dark so I probably didn't see it at its best. I was generally using my 2" 30mm 82° Explore Scientific and Baader Hyperion 8-24mm Zoom eyepieces with a DGM NPB filter where required, although my 42mm GSO superview also got a workout and was surprisingly good - I think I may even be able to stretch to the GSO 50mm for some 36x low mag cruising in the future as I was struggling to get the whole Pleiades in the field of view. Coma was evident if not fierce (to my relatively untrained eye), but at this stage I'm not such a stickler for visual perfection and it, to my mind at least, did not detract from what was a truly fantastic night of viewing. I can see myself getting a coma corrector at some point in the future just to cover all my bases though. The height of the focuser also means that you generally spend the night on your feet, which I found probably more comfortable than sitting on a chair hunched over the eyepiece.
Overall, I love this scope despite its size and apparent mobility issues. Sure, it takes a bit more time and effort to set it up than a smaller scope as the pieces themselves are somewhat heavy and cumbersome, and you'd be hard pressed to keep the scope fully assembled even on a large trolley unless you were close to your observing site, but to my mind the views it produces are well worth the extra effort. Having said that, this is certainly not a telescope I would ever recommend for anyone with any sort of back/arm/upper body issues, limited storage space, hernias, haemorrhoids, multiple steps around your house, or a wife with a penchant for withering stares and disparaging remarks. Clear skies to all.
Last edited by gaseous; 25-01-2017 at 11:12 PM.
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