Sky-Watcher Stargate 400P SynScan FlexTube Dobsonian Telescope

Designed for visual observation of the Moon, planets and deep-sky objects, Sky-Watcher Stargate 400P SynScan FlexTube combines 406 mm parabolic optics with a 1650 mm focal length and an f/4.1 focal ratio. Its light-gathering capacity is stated to be 34.5 percent greater than that of a 300 mm instrument.

All-metal FlexTube structure combines rigidity with reduced storage dimensions. The optical tube can be retracted quickly for easier transport and storage. When extended, the three-point system is designed to prevent lateral movement and flexure while maintaining collimation.

Complete telescope assembly can be achieved in less than 30 minutes. The optical tube length ranges from 850 mm when retracted to 1500 mm when extended.

Metal Go-To alt-azimuth mount is motorised on both altitude and azimuth axes. It can automatically slew to and track more than 42,900 celestial objects using the supplied SynScan handset database.

Built-in Wi-Fi also allows the telescope to be controlled from an iOS or Android mobile device using the free SynScan app. The application provides more than 10,000 objects, several alignment methods, a selection of the best objects visible during the night, celestial object identification, Point and Go, remote control over the Internet, user-defined objects and Pointing Accuracy Enhancement.

Freedom-Find dual-encoder technology allows manual movement on both axes without losing alignment or positional information. The telescope can be pushed close to a target before the computerised system completes the final positioning.

Fully manual operation is also possible when the power is switched off and the clutches are loosened. This configuration allows the telescope to be used as a manual Push-To instrument.

Parabolic primary mirror uses a patented weight-saving design. Its geometry brings incoming light rays to the same focal point to eliminate spherical aberration and produce detailed, sharp and high-contrast images.

Primary and secondary mirrors are manufactured from low-expansion borosilicate glass similar to Pyrex. Its low thermal expansion coefficient supports faster cooling and helps the mirrors retain their shape while reaching thermal equilibrium. This thermal stability reduces distortion without relying on a cooling fan.

RAQ Radiant Aluminium Quartz coatings are applied to the primary and secondary mirrors. Combining layers of aluminium, dielectric tantalum pentoxide and silicon dioxide, this coating system provides up to 94 percent reflectivity and long-term protection for the optical surfaces.

Dual-speed 2-inch Crayford focuser supports precise focusing adjustments. Adaptors for 1.25-inch and 2-inch eyepieces are supplied.

Drive system uses a worm gear and timing belt transmission combined with 1.8-degree stepper motors controlled through 256 micro-steps. Stated pointing accuracy is 5 arc-minutes RMS.

Supplied equipment includes 12.5 mm and 20 mm eyepieces, a 1.25-inch collimating eyepiece, a 9x50 finderscope, a direct SLR camera connection, a fabric light shroud and a universal smartphone adaptor compatible with devices measuring between 54 and 90 mm in width.

Connections consist of a USB-B port, a handset port and a power input port.

Technical specifications

• Optical design: Newtonian reflector on a motorised Dobsonian mount
• Primary mirror diameter: 406 mm
• Focal length: 1650 mm
• Focal ratio: f/4.1
• Primary mirror: parabolic
• Primary mirror design: patented weight-saving structure
• Primary and secondary mirror material: low-expansion borosilicate glass
• Secondary mirror diameter: 120 mm
• Mirror coating: RAQ Radiant Aluminium Quartz
• Stated reflectivity: up to 94 percent
• Magnifications with supplied eyepieces: 82.5x and 132x
• Highest potential practical power: 812x
• Supplied eyepieces: 12.5 mm and 20 mm
• Stated apparent field: 70 degrees
• Supplied collimating eyepiece: 1.25-inch
• Focuser: dual-speed 2-inch Crayford
• Eyepiece adaptors: 1.25-inch and 2-inch
• Finderscope: 9x50
• Direct SLR camera connection
• Universal smartphone adaptor included
• Compatible smartphone width: 54 to 90 mm
• Fabric light shroud included
• Tube structure: fully collapsible metal FlexTube
• Tube locking system: three rigid points
• Retracted optical tube length: 850 mm
• Extended optical tube length: 1500 mm
• Stated assembly time: less than 30 minutes
• Mount: metal Go-To alt-azimuth
• Motorised axes: altitude and azimuth
• Transmission: worm gear and timing belt
• Drive system: 1.8-degree stepper motors
• Motor control: 256 micro-steps
• Encoder technology: Freedom-Find dual encoders
• Manual movement without losing alignment
• Manual operation available with power switched off and clutches loosened
• Stated pointing accuracy: 5 arc-minutes RMS
• Azimuth gear ratio: 854.182
• Altitude gear ratio: 1655.636
• Hand controller: computerised SynScan handset
• Hand controller database: more than 42,900 objects
• Hand controller catalogues: Messier, NGC and IC
• Built-in Wi-Fi
• Mobile control: free SynScan app for iOS and Android
• SynScan app database: more than 10,000 objects
• Deep-sky objects in the app: 10,759
• Deep-sky catalogues: Messier, NGC, IC and Caldwell
• Named stars in the app: 305
• Double stars in the app: 55
• Solar System objects: seven planets, Sun and Moon
• Compatible with third-party planetarium software
• Alignment methods: one-star, three-star, brightest-star and North-Level alignment
• App functions: Tonight’s Best, Point and Go, celestial object identification, remote control over the Internet, user-defined objects and Pointing Accuracy Enhancement
• Quiet operation
• Connections: USB-B, handset port and power input
• Power requirement: 11 V DC at 5 A to 15 V DC at 3 A
• Stated light gathering: 34.5 percent greater than a 300 mm instrument
• Overall weight: 50 kg