Sky-Watcher Skyliner-400P FlexTube: 16 inch, the pinnacle of visual observation
The Sky-Watcher Skyliner-400P FlexTube has a 406 mm (16-inch) parabolic mirror and a focal length of 1,800 mm (f/4.4). This is the class where you can see firsthand what smaller telescopes only promise in photos. The FlexTube system extends the tube from 169 to 107 cm, and the dual-speed 10:1 Crayford focuser makes micro-focusing on this bright-light system effortless. To be honest: this is an instrument weighing a total of 66 kg, which is to be expected in this class.

What do you see through the Skyliner 400P?
More than two and a half times more light than a 10-inch. Dark dust lanes in the Andromeda Galaxy, fine filaments in the Orion Nebula, color impressions in bright nebulae, and globular clusters that fill the entire field of view. On planets: sharp edges, rich band details, and tiny moons. This is the size at which experienced observers say objects begin to feel “three-dimensional.”.
Dual-speed focuser and complete set
The 2-inch dual-speed 10:1 Crayford focuser provides the fine adjustment that an f/4.4 mirror deserves: one turn coarse, ten turns fine. The set includes two 70-degree Wide Angle eyepieces (90x and 144x), a 9x50 finderscope, and a universal smartphone adapter.
This is how to get the most out of this telescope
- To them, in part: Buis 30.5 kg, rockerbox 35.5 kg: plan a fixed location or a trailer strategy; this will be lifted by two people. Plan the route to your observation spot accordingly.
- Close the open section: A light shroud around the extended truss keeps stray light and dew out. The standard upgrade for FlexTube models.
- Allow for at least an hour to cool down For the large mirror, especially in winter.
- Collimation at f/4.4 is a fixed ritual on transport; our guide to collimation It takes two minutes.
For whom yes and for whom no
Hello The driven visual observer with a fixed dark viewing spot or transport assistance, for whom light output is the only true criterion.
Not if the logistics are still a question mark: a Skyliner-200P Classic One that stands outside every week beats a 16-inch one that stays inside. If you want a GoTo on this scale, there's the 400P SynScan version. Long exposures belong to the smart telescopes.
Featured accessories
These accessories add the most after purchase:
- Moon Filter 13%: With this mirror size, the moon is blindingly bright. The Omegon Moon Filter 13% (1.25 inches) dims the light and increases the contrast. More explanation is in our Moon filter guide.
- Cheshire eyepiece the Sky-Watcher Cheshire Eyepiece Aligning the mirrors is more accurate than the included tools. With these fast opening ratios, it's not a luxury but a essential piece.
Technical specifications
| Feature | Specification |
| Telescope type | Newtonian reflector (Parabolic primary and secondary mirror) |
| Main mirror diameter | 406 mm (16 inches) |
| Tube design | Patented FlexTube™ (Retractable Truss Tube System) |
| Mirror material | Low-Expansion Borosilicate Glass |
| Focal length | 1800 mm |
| Opening ratio | f/4.4 |
| Mirror coatings | Radiant™ Aluminum Quartz (RAQ™): up to 94% light reflectance |
| Light output | 34.5% more light-gathering power than the 350 mm model |
| Brake caliper bracket | 0.5 mm ultra-thin spider supports |
| Included eyepieces | 12.5 mm & 20 mm (1.25″): 70° Super Wide Angle |
| Included magnifications | 90x and 144x |
| Maximum useful magnification | 812x (Potential) |
| Focuser | Dual-Speed 2″ 10:1 Crayford focuser (ultra-precise micro-focus) |
| Included adapters | Both 2″ and 1.25″ adapter with non-marring brass compression ring |
| Seeker | Large 9×50 optical finder scope with crosshairs |
| Camera connection | Direct SLR/DSLR connection possible |
| Smartphone adapter | Universal (suitable for phones between 54 mm and 90 mm wide) |
| Material optical tube | Rolled steel finished in Black Diamond metallic |
| Tube diameter | 540 mm |
| Optical tube assembly (OTA) length | Extended: 1685 mm / Retracted: 1071 mm |
| Mounting type | Wooden Dobson with Tension Control & Accessory Plate |
| Diameter of the base | 840 mm |
| Weight optical tube assembly | 30.5 kg |
| Rocker box weight (base) | 35.5 kg |
| Total weight | 66 kg |
Included in the box
- Sky-Watcher Skyliner-400P FlexTube Optical Tube Assembly with Rockerbox and Tension Control Handles
- Eyepieces: 12.5 mm & 20 mm (1.25″): 70° Super Wide Angle
- Finder: Large 9×50 Optical finder with crosshair
- Focuser: Dual-Speed 2″ 10:1 Crayford focuser (extremely precise micro-focus)
- Adapters: Both 2″ and 1.25″ adapters with scratch-free brass compression ring
- Smartphone Adapter: Universal (fits phones between 2.1 inches and 3.5 inches wide)
Honest advice from observers
We sell and use the Sky-Watcher line ourselves. In our Sky-Watcher merk Guide We'll explain which series are strong and which you'd rather skip. View the full range on our Sky-Watcher merk Page or compare all models in our Dobson assortment. If ordered before 11:59 PM, it will be delivered quickly, in the Netherlands and Belgium. Not sure about the size or version? Call or email us: these are purchases we're happy to help you think through.







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