By Geoff Gaherty
Toronto Centre RASC
I've used a number of 4" to 4.5" telescopes over the years, and usually found them OK for casual looks at the Moon, planets, and brighter deep sky objects, but basically unsatisfying in the long term. On the other hand, almost all the 6" or larger scopes I've used have been capable of excellent views of both shallow and deep sky objects. Somewhere between 4.5" and 6" of aperture, there seems to be some sort of threshold between "casual" scopes and "serious" scopes..."serious" in the sense that they offer much wider opportunities for observations. I have almost never used a scope in the threshold zone, and so looked forward to testing this new telescope manufactured by Sky-Watcher.
The Sky-Watcher 130 looks at first glance like most of the common 4.5" f/8 reflectors, except that its tube is somewhat shorter (61 cm long) and wider (16 cm in diameter). The mount is a standard small equatorial, specifically the EQ-2. The rolled steel tube is finished in the usual Sky-Watcher blue enamel, and the focuser is the standard mostly-plastic 1.25" job found on most scopes this size. Because of the mirror's short 650 mm focal length, this will yield a 2.5° field with a wide field eyepiece, though even the 25 mm eyepiece provided yields an impressive 2° field.
The rest of the components are rather better than usual: the mirror cell is all metal and very solid, the diagonal mirror is supported by a new design of spider with very thin flat arms, not the rods or square struts I'm used to seeing. The finder scope is a standard Synta 6x30 mounted in a dovetail with their unique two bolt adjustment operating against a spring. This latter puts all of their finders into a class of their own for the user friendliness of their alignment. The scope comes with two very nice Plössl eyepieces, 25 mm and 10 mm, of a new design, similar to the old Celestron "silver-tops," and the usual cheap plastic 2x Barlow. Every time I get one of I always give it a try, but they always introduce so much chromatic aberration into what is basically a colour-free system that I never use them a second time. The scope also comes with a screwdriver and three wrenches.
There was no instruction manual with this sample, but assembly was no different than any similar scope and gave me no problems. Collimation was almost exactly right, out-of-the-box. It appears as if this scope is supposed to be "factory collimated": the back of the mirror cell is covered by a thin metal plate attached by three Phillips-head screws which must be removed to access the push-pull collimation adjustments. These are three pairs of bolts, one of each pair with a Phillips head and the other with a tiny Allen key head. The mirror is held by three clips against cork pads in a metal cell. The cell holds only the outermost centimeter of the mirror; the rest of the back of the mirror is completely open once the metal backing plate is removed. If this were my scope, I'd leave the backing plate off permanently to allow the mirror to reach thermal equilibrium quickly.
Since the collimation of the secondary was fine, I didn't attempt to adjust it, but it looks like the standard arrangement of three small bolts against one large central bolt. As I already mentioned, the spider is really excellent: fully adjustable and with four thin vanes holding the mirror rigidly in place. Unlike a lot of small Newts, its secondary mirror appears to be exactly the right size, the outer edge of the primary being just visible when viewed from prime focus.
With the telescope assembled, I put it outside in the -10C cold to acclimatize. I tried it on the Moon, Jupiter, Saturn, M57, M45, M31 and M32. Once the tube currents from cooling down had dissipated, the performance on Jupiter and Saturn was excellent. Detail was visible within Jupiter's North and South Equatorial belts. Turning to Saturn, Cassini's division was visible right the way around the rings, the shadow on of the globe on the rings was clear despite being only a few days past opposition, the moons Titan and Rhea were easy, and the South Equatorial Belt was plainly visible on the planet itself. I was able to split Epsilon Lyrae into its four components at 162x (using my 4 mm Radian eyepiece, since the supplied Barlow was useless).
So, using the standards I mentioned at the outset, this scope clearly belongs with the 6"-and-larger "serious" group. The mount is a bit on the light side, but its slow motions work smoothly and well, so vibration is not a serious issue. Its compact size and light weight (12.5 kg) make this an ideal "grab-and-go" scope; it will end up being used a lot more often than a larger but more cumbersome scope on the one hand, or a smaller scope with so-so views on the other. I've left the best news for last: the price on this scope is $400-500 Canadian, so it's priced with the 4.5" reflectors but offers performance similar to 6" reflectors. I like it a lot, and I expect many others will too.
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