SkyWatcher Skyliner-250PX FlexTube

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Magazine Verdict: 
SkyWatcher Skyliner-250PX FlexTube

Vital Stats

10 inches (254mm)
Focal Length: 
1,200mm; f/5
10mm and 25mm, 1.25-inch fit
9x50 right-angle
Optical Vision Ltd
01359 244200

The Sky-Watcher integrates some of the best aspects of other Dobs. The primary mirror is protected inside a half-length rigid tube, while the secondary mirror is mounted in a short tube, linked by three sliding truss tubes. You can retract the tube to just 80cm from its full length of 112cm, making it easier to store and transport. The primary tube has a tight-fitting plastic cover, while the secondary tube has a fetching black fabric ‘shower cap’ to keep the dust at bay. The sliding tubes work smoothly, with T-clamps to lock them in position.

Secondary mirror collimation was jumpy, but once achieved, the beam from our laser collimator held its central position throughout the range of sliding truss positions, suggesting that you could take the tube from your car, lift it into the mount, extend it, and start observing straight away.

The mount doesn’t have a roller azimuth bearing. Instead the base just has three Teflon pads; a simple approach and we loved the slightly stiff (but smooth) action it gave, which complemented the plastic altitude bearing arrangement. The resulting friction can be adjusted using one of the threaded locking handles, which secure the scope and provide two useful lifting points for manhandling the whole setup into position. We found the extra friction became necessary since the scope was a little top heavy, especially with large eyepieces, but it was easier to change eyepieces without the scope being knocked off target.

The 2-inch Crayford focuser functions as it should, but lacks some of the refinements seen on other scopes. A 2-inch and 1.25-inch adaptor are provided, which use set screws rather than compression rings, and the design prohibits changing to another type of adaptor. The view through the 9x50 right-angle finderscope is the same way up as the sky, which is a more intuitive arrangement when hand-pushing from star to star. The finder’s optics appeared slightly better than the GSO’s.

Set up and go
The mount was accompanied by a helpful set of instructions, and thoughtfully the scope arrived with all the tools required. Sky-Watcher includes two 1.25-inch eyepieces – a 10mm and a 25mm Plössl – both of which worked very well. The 25mm eyepiece produced a dazzling Beehive Cluster with excellent star colours. The 10mm provided enough magnification for planetary use and we were able to discern surface detail on Mars and resolve Saturn’s rings and major moons. Switching to our wide-field test eyepiece allowed us to compare the deep-sky performance. Our 6mm eyepiece provided good separation of the double star Algieba and a sharp view of Saturn.

When it comes to those little extras, we appreciated the provision of a couple of plastic knobs close to the focuser – convenient for slewing the scope – but noted the lack of a cooling fan.

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A version of this article appeared in the June 2010 issue of Sky at Night Magazine

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