SkyTee-2 Alt/Az Mount Review

SkyTee-2 Alt/Az Mount Review

By CN user “ScrewLoose”

Introduction

This review turned out to be much longer than I anticipated, so I decided to add this short introduction to help readers to decide whether to read all the way through.

I bought this mount, after much agonising, as the mount for my first "real" telescope. This review should be particularly useful for beginners who are grappling with the decision of what kind of mount to buy, but it should also be useful to anyone who's considering adding an alt/az mount and might be interested in the TS-Optics AZ5ST or SkyTee-2, or who already has one of these mounts.

I have also written a detailed description of dismantling and re-assembling this mount, which I will post if there's sufficient interest (I'm not sure how common these mounts are).

Overall, the SkyTee-2 mount functions well and is good value for money. While purchasers of earlier models have reported a handful of issues over the years, these appear to have been resolved in the current model. I'm confident that this mount will meet my needs for many years to come.

The Purchasing Decision

Towards the end of 2020, I decided to buy an Astro-Tech AT102ED refractor with a Voyager 2 mount. Somehow, this turned out to be much more difficult than I anticipated and I ended up buying a used Skywatcher 120ED locally instead.

My next task was to find a suitable mount for this scope. This turned out to be surprisingly difficult too - especially for a novice like me. Just deciding whether it should be an equatorial or alt/az mount was difficult. Eventually, I came to the conclusion that "simple is better" and that it would be a mistake to be over-ambitious, so I decided to stay with an alt/az mount.

Unfortunately, the Voyager 2 and its competitors seem to top-out with payloads of around 5.4 kg (12 lb), and it quickly became apparent that this was not going to be enough to support a SW120. Mine weighs 6.8 kg (15 lb) including typical accessories.

I was surprised by the limited choice of alt/az mounts in the next tier - they very quickly reached a price where I felt that I might as well jump straight to a fancy EQ mount. I eliminated the Vixen Porta II and the Explore Scientific Twilight II as being not sturdy enough, and then the Desert Sky DSV-3, Losmandy AZ8, and Rowan AZ100 for being too expensive. This left me with the Stellarvue MC-2 and the TS-Optics AZ5ST.

My first choice was the not-made-in-China Stellarvue MC-2 which was offered bundled with a decent Celestron tripod, but when I went to place my order, that combination had disappeared and the head was available only with Stellarvue's own, more expensive tripod. This left the TS-Optics AZ5ST. It was around this time that I discovered that First Light Optics (FLO) in the UK carried essentially the same mount branded as the SkyTee-2. There seemed to be several advantages to buying from FLO, so I got in touch.

FLO listed the SkyTee-2 as a head only, which was in stock, or as a head and tripod, which was out of stock but due in within a couple of weeks. The tripod is the same one that's supplied with a number of more expensive Skywatcher heads and the bundled price was a big improvement over buying a tripod separately, so I went ahead with the back-order.

There are several comments that I would like to make about buying from FLO: first, they are very easy to deal with. The 8 hour time difference meant that we rarely had more than one email each in any given day, but they were always prompt, attentive, and to the point. Second, UK prices include that country's value added tax (VAT). FLO removes this tax for export sales; it will be replaced by whatever import and sales taxes your own jurisdiction cares to apply. Since VAT is 20%, this is a big reduction and goes a long way towards off-setting the shipping cost. Shipping was by DHL, which isn't typically as slick as UPS or FedEx, but still managed to deliver to my door within six days.

The Product

The packages (three in total) arrived with some slight damage on one side of the tripod's cardboard shipping box, but there was no damage inside. My only other concern with the packaging was with respect to the third box which contained a number of small items that I had included in the order - the items were packed in foam chips, which I find particularly objectionable.

Neither the SkyTee-2 head nor the tripod had any accompanying documents whatsoever (excluding the shipping docs on the outside of the boxes) - no assembly instructions, no warranty cards, not even a market research form dressed up as a "product registration". Fortunately, assembly and use are both fairly obvious.

The tripod is simple, but sturdy. It has 1.75" diameter stainless steel tubular extending legs that fit into cast sockets at each end. The feet have rubber tips so that the tripod could be used on a deck, for example, without damaging the surface. There's a cast spreader which locks the tripod's legs in the spread position and provides half a dozen or so holes for eyepieces. Although the casting has ribs for bracing, it's quite thin and I wondered how much force could be applied before it would break. Also, the paint chips quite easily.

The SkyTee-2 head was well packaged in moulded styrofoam. I prefer to avoid styrofoam packaging if I can, but in this instance I intend to keep it in case I decide to sell the head in the future and need to ship it. The head was supplied with two dovetail saddles (one mounted and one loose), a 20 mm diameter counterweight bar, and a 2 kg counterweight. The latter was unexpected! The loose saddle included two socket cap mounting screws and a wrench.

True to its name, the head is essentially a 'T' shape. The bottom of the leg of the 'T' locates in a recess in the top of the tripod. It's a very sloppy fit, but seems to lock down well enough. The crossbar of the 'T' has a tubular shaft running along the middle of it which carries end caps at both ends for mounting the saddles. The end caps are locked to the shaft so that they move together and will keep two scopes in sync once set up correctly.

Altitude adjustment comprises a simple lever-clamping mechanism and a worm-drive fine adjustment mechanism. With the clamping mechanism released, the mount rotates freely; with the clamping mechanism applied, the mount is locked and altitude may be adjusted only via the knobs on the worm-drive mechanism. There's a similar worm and lever mechanism for azimuth adjustment. This arrangement provides a rapid pan/tilt ability as well as fine alt/az control.

The crossbar of the 'T' also carries a pad for top-mounting a scope or accessory. This top-mount assembly doesn't have a worm-drive, but it does have locking levers for both altitude and azimuth. It also has a threaded hole on the opposite side to the mounting pad that accepts the counterweight bar. This is good news, because anything mounted on the top pad will go out of balance very quickly as soon as it moves away from the horizontal in the absence of a counterweight.

I'm using the mount with my SW120 refractor mounted on the left-hand saddle, which I'll refer to as the primary saddle or end cap. This is with the top mounting pad to the right of the leg of the 'T'. The secondary end cap has a tapped hole on its horizontal axis which accepts the counterweight bar. The SkyTee-2 can easily carry my SW120 without a counterweight, although in my opinion it's good practice to use one. A threaded plug is provided for when a counterweight bar isn't used.

Setting Up

When assembled and with my SW120 mounted to the primary dovetail saddle, all movements were smooth and with no perceptible play. However, movement was also quite tight, which makes it impossible to balance the scope accurately while on the mount. To what extent this really matters with a manually operated mount might be a matter of conjecture, but having the balance about right will be easier on the altitude worm drive and locking mechanism, and will reduce the torque on the central shaft.

I determined the approximate point of balance simply by placing the scope with its dovetail rail on pencil on a flat surface and using the pencil as a pivot. I did this for the basic scope and again when fitted with typical accessories, and then stuck a couple of pieces of masking tape on the scope's dovetail rail to mark the balance points.

If you find the movement too tight, it's not difficult to partially dismantle the mount and ease the locking collar that controls the tightness, but that would be entirely at your own risk. I decided to completely strip, clean, and re-assemble my mount. This might not be really necessary, but now I understand how the mount works and I know that everything is to my satisfaction. I did find some blow-holes on the interior surface of one of the castings. While they don't affect the performance of the mount, they do reflect the rather poor level of manufacturing technology used in the manufacturer's foundry.

With my SW120 mounted and balanced with my Fuji camera body attached to the 2" focuser, or with a 2" diagonal and eyepiece, the accessories can contact a tripod leg when the scope is vertical. With the accessories removed and the scope consequently out of balance, if the altitude locking lever is accidentally released, the scope can rotate downwards and the dew shield contact a tripod leg. I estimate that an 8" extension column would eliminate this risk, so I might think about making one sometime. Note that your scope might be different.

Counterweights

With my scope weighing nearly 7 kg (15 lb) all-up, I was concerned about the need for a counterweight. The bearing surfaces in the SkyTee are very basic - just machined bores in the castings to act as journal bearings and very thin plastic washers for thrust and friction, and those plastic washers run on some rather imprecise surfaces. I was concerned that off-set loads on all these surfaces would lead to premature and uneven wear. The 2 kg counterweight supplied with the SkyTee hadn't sounded heavy enough to me, so I had ordered a pair of Skywatcher weights (1.8 kg and 3.4 kg) from FLO. More on this in a moment.

With the telescope fully loaded with accessories and mounted on the primary (left-hand) saddle, I set the scope parallel to the two adjacent feet of the tripod and then put bathroom scales under the third foot. I then rotated the head 180° about the azimuth axis so that the scope was over the third foot and inserted the bathroom scales again. Next I started adding and adjusting counterweights and repeating both measurements until they were about the same. This occurred when I mounted the pair of Skywatcher counterweights at the end of the counterweight bar. To get the balance just right, I used the 3.4 kg weight the wrong way around so that the bar's end-stop wasn't recessed in the weight's counterbore.

The Skywatcher weights were on a longer delivery schedule than the SkyTee mount, but ended up shipping a lot sooner than I expected and took only three days to arrive. My immediate reaction was that they are better quality than the SkyTee weight. The latter came with a thumbscrew about 25 mm too long, a steel dowel to avoid marking the counterweight bar with the tip of the thumbscrew, and a very thin coat of paint.

Each Skywatcher weight came with a thumbscrew which has been turned down for something over half its length, which means that you don't have to spend so long spinning it into the thread in the weight before you reach the bar. The thumbscrew also has a hard plastic insert in the end which bears on the counterweight bar, instead of a separate steel dowel. However, the plastic insert doesn't grip very well. The Skywatcher weights are counterbored from one side. The resulting recess allows the weight to pass over end-stop of the bar, thus enabling the weight to create more leverage than would otherwise be the case.

I've mentioned above that the counterweight bar can also be used to balance an instrument mounted on the top mounting pad. The diameter of the SkyTee counterweight and the length of the bar are such that they will clear the rest of the mount in all possible alt/az positions when the 2 kg weight supplied is at the end of the bar. However, after the weight is raised about 38mm (1.5"), it will begin to interfere with the azimuth fine adjustment knobs. If you think you might need a counterweight that's heavier than 2 kg, consider buying the Skywatcher pair.

The Skywatcher weights are 120 mm diameter instead of the SkyTee's 100 mm, and a weight used at the end of the bar will foul the top of the tripod if it's fitted with the bar's end-stop inside the weight's counterbore. However, if a Skywatcher weight is put on upside down so that the end-stop isn't recessed, the weight will just clear the top of the tripod. There's room to use both Skywatcher weights without fouling the azimuth fine adjustment knobs,. This is probably enough to balance around a 6 kg payload (as a rough estimate), which is more than I'd want to mount on the top pad anyway.

Past Issues

The SkyTee-2 has been in production for some years and has a number of known problem areas which I was keen to investigate:

1.     Many purchasers report that a highly viscous and sticky grease is liberally applied to the internal surfaces during manufacture, and some users have found machining swarf mixed in with the grease. While the grease certainly lives up to its reputation, I found no traces of swarf or any other manufacturing debris. Incidentally, the grease is a damping grease which should not, in my opinion, be replaced with conventional grease.

2.     I have read comments about the dovetail tail saddles not opening wide enough to readily accept a dovetail rail, and also of the threads in the locking knobs failing and causing the telescope to fall to the ground. On my SkyTee-2, both issues have been resolved. In particular, the aluminum locking knobs have been fitted with Helicoil-type steel inserts, which should provide plenty of resistance to stripping. The knobs are the same as the ones used on my SW120's rings, which also have thread inserts. Overall, while the fit of the dovetails themselves might not be quite perfect, they seem perfectly adequate in my opinion and I see no reason to replace them.

3.     The female thread for the locking lever for the top mount has been known to strip, allowing a mounted telescope to rotate suddenly with significant potential for damage. In my experience, screw threads made in China are often not just substandard, but can be almost useless. While this might have been the case with the SkyTee in the past, the threads in mine are serviceable and this locking thread in particular is snug - although the female thread hasn't been fitted with an insert.

4.     I've seen a couple of comments about the female threads in the worm-drive mounting brackets stripping due to inadequate thread engagement with the male screws. This appears to have been rectified by using longer screws. However, the brackets are quite thin and might be made from a questionable grade of aluminum, so care should be taken when tightening a small, steel screw.

5.     Earlier models were not supplied with the end cap drilled and tapped for a second dovetail saddle, so purchasers had to do this themselves if they so wished. These holes are now provided as standard. Two saddles can be roughly aligned by removing the primary saddle and rotating it through 120° in the appropriate direction, and then tightening or loosening the end cap. While this might not sound like a great solution, it will work well enough thanks to the sticky, gap-filling properties of the damping grease.

6.     An observation of my own: the azimuth locking lever interferes with the fine adjustment knobs while panning. Fortunately, the knobs are a sloppy fit when released and are readily pushed aside by the knobs.

Conclusions

It's now summer and the air is full of dust and heat-haze, so it's going to be some time before it will be worth trying any observing, but my preliminary impressions are favourable and I'm feeling confident about the mount's ability to support and direct my telescope.

While the mount certainly isn't a sophisticated example of precision engineering, it's simple and sturdy. Its made-in-China weaknesses are evident, but the manufacturer appears to have listened to past criticisms and to have done something about them. The whole mount has a solid feel to it and the movements are satisfyingly smooth. I like the worm-drive fine adjustments too.

The whole assembly is towards the top end of the grab-and-go scale. A smaller scope would accept a smaller mount and thus be lighter and easier, but it is still feasible with a 120 mm refractor. I have a Pelican case on order, which I will use to house the SkyTee head and my various eyepieces and accessories and to make transportation easier.

The mount is quick and easy to set up and, even with counterweights attached, I can pick the whole assembly up by grabbing the top of the tripod and walk with it. It's a fairly clumsy exercise, but feasible for a short distance for the purposes of repositioning.

Overall, I think that this mount is good value for money and a good choice for my purposes. I'm confident that the mount will be more than adequate for my needs.