Sky-Watcher Flextube 350P SynScan

At a Glance

• Aperture: 356mm (14-inch)
• Focal length: 1650mm
• Focal ratio: f/4.6
• Focuser: 2-inch dual-speed Crayford-style, 1.25-inch adapter supplied
• Finder: 9x50 straight-through
• Mount: Computerised GoTo Dobsonian, dual-axis tracking, 42,900-object database

Product Overview

The Sky-Watcher Flextube 350P SynScan is a 356mm (14-inch) computerised GoTo Dobsonian with a collapsible truss tube. It runs 1650mm of focal length at f/4.6 and gathers 2507 times the light of the unaided eye, with a SynScan hand controller and built-in Wi-Fi driving it across 42,900 catalogued objects.

It sits between the 300P and the 400P in the range, and shares the larger scope's dual-speed focuser rather than the single-speed unit fitted to the 250P and 300P. The truss retracts for transport, holds collimation through the cycle, and the telescope travels as two pieces rather than a bundle of struts.

Who It Is For

This is a good match if you:

• Want large-aperture deep-sky performance without stepping up to the size and mass of a 16-inch.
• Observe from a fixed site, or have a level path and a way to wheel it out.
• Value fine focus — at f/4.6 the dual-speed focuser is doing real work every session.
• Want computerised finding on a big Dob while keeping the freedom to push it by hand.

Key Features and Design

• 2507x the light grasp of the unaided eye: 36% more than the 300P, which shows in faint galaxy detail and dimmer planetary nebulae.
• f/4.6 over 1650mm: fast enough to hold a usable true field at this aperture rather than being all magnification.
• Dual-speed Crayford focuser: a fine-focus reduction the 250P and 300P do not have — at f/4.6 the depth of focus is shallow, and coarse-only focusing costs you sharpness every time.
• Patented collapsible truss tube: retracts for transport and storage while retaining collimation, and provides back focus for camera use.
• Patented Freedom Find dual encoders: push the tube by hand at any point with no re-alignment afterwards.
• SynScan GoTo with built-in Wi-Fi: hand controller and wireless control, with pointing accuracy published to 5 arc minutes.
• Patented tension control handle: holds aim at this mass when a heavy eyepiece goes in.

Optical and Mechanical Design

Optically a fast Newtonian: 1650mm over a 356mm parabolic primary gives f/4.6. Two mirrors and no lenses means no chromatic aberration at any magnification, and the fast ratio keeps the tube shorter than the aperture would otherwise require.

The focuser is the detail worth understanding here, because it is where this model separates from the two below it. A fast focal ratio produces a shallow depth of focus — the range of drawtube travel over which the image is genuinely sharp is small. A dual-speed focuser adds a reduction gear so the final adjustment can be made in small, controlled increments rather than by nudging a single-speed knob and hoping. On a 14-inch instrument that resolves fine planetary detail, that is the difference between reaching the telescope's potential and getting close to it. Everything else follows the series: truss geometry that returns to position on extension, encoders reading both axes independently of the motors, and a rocker box carrying the mass low on Teflon bearings.

Recommended Uses

• Faint deep-sky observing: galaxy groups, dim planetary nebulae, and structure within brighter galaxies.
• Globular clusters: resolved across the core under reasonable conditions.
• High-power planetary work: the resolution to exploit steady seeing, with the focuser to place it precisely.
• Outreach and club nights: tracking holds the object while a queue works through the eyepiece.

Compatibility and Accessory Notes

Supplied with a 9x50 straight-through finderscope, 12.5mm and 20mm four-element 1.25-inch Plössl eyepieces, and the SynScan hand controller. The 2-inch focuser accepts any standard 2-inch eyepiece, with the supplied adapter for 1.25-inch.

At f/4.6 eyepiece correction matters — simpler designs soften noticeably at the field edge, and a well-corrected wide-field eyepiece is where the first upgrade money goes. A coma corrector is worth considering at this focal ratio. Power is 10 to 15 V DC at 1 amp through a 2.1mm centre-positive plug, and a light shroud over the open truss is close to essential at this size. If you would like help specifying eyepieces, a coma corrector, power, or transport, get in touch and we will work through it with you.

Good to Know Before You Order

• Plan the logistics first. A 14-inch Dobsonian is two substantial pieces. Storage, the route to your observing spot, and a dolly are worth settling before it arrives.
• It needs power. The GoTo runs on 10 to 15 V DC, so a capable field battery is part of the kit.
• The eyepiece sits high near the zenith, so an observing step or ladder is normal practice at this aperture.
• Deep-sky imaging is limited by the mount, not the optics. Back focus is available and tracking is dual-axis, but an alt-azimuth mount rotates the field over long exposures. Lunar and planetary capture suits it well.
• Cool-down is significant. A 356mm mirror needs real time to reach ambient before it delivers its resolution.

Frequently Asked Questions

Is it difficult to set up?

Operating it is straightforward — extend the truss, seat the tube, connect power, run a two-star alignment. The demanding part is handling rather than operating, since this is a large telescope in two heavy pieces.

Does this model have the dual-speed focuser?

Yes. The 350P and 400P are fitted with a 2-inch dual-speed Crayford-style focuser; the 250P and 300P are single-speed. At f/4.6 the fine-focus reduction earns its place.

Can I move the telescope by hand?

Yes. Freedom Find dual encoders read position independently, so pushing the tube to a target does not cost you the alignment.

Can I use it for astrophotography?

Lunar and planetary imaging, yes. Long-exposure deep-sky imaging, no — field rotation is inherent to an alt-azimuth mount.

What comes in the box?

A 9x50 straight-through finderscope, 12.5mm and 20mm 1.25-inch Plössl eyepieces, and the SynScan hand controller. You supply a 10 to 15 V DC power source.

How does it compare with the 300P and 400P?

The 300P is 305mm at 1840x and single-speed focusing; the 400P is 406mm at 3257x. This sits between them at 356mm and 2507x, sharing the 400P's dual-speed focuser while remaining appreciably easier to move.

Bottom Line

In short: a 356mm f/4.6 collapsible GoTo Dobsonian with dual-speed focusing and encoders that let you drive it or push it as you prefer. It delivers most of what a 16-inch shows while staying meaningfully more manageable, provided you sort out power, transport, and somewhere to keep it.