Sky-Watcher FlexTube 350/1650mm Dobsonian Telescope

It includes a WiFi card, which allows you to control the telescope using a smartphone.

• Very large diameter, perfect for deep sky observation.
• Ideal for planetary and lunar observation.
• Automatic pointing (GOTO) and motorized tracking
• Detachable base for easy transport by one person.

In recent years, Dobsonian fever has increasingly captivated amateur astronomers, Those who understand that the most intense observational experiences are achieved with large-diameter telescopes. High-resolution planetary observations of Jupiter, Mars, Saturn (and the Moon), while clusters, nebulae, and galaxies number in the thousands, can be observed with a 350 mm diameter instrument. Without motors or electronics, Dobsonian telescopes are the instruments that provide the most light for a given budget. compared to any other type of instrument (most of which are motorized and GoTo).

However, the pursuit of a larger aperture comes with a major drawback: bulk! To observe under optimal conditions and fully exploit the potential of your instrument, far from city lights, it's essential to transport the equipment in a vehicle and then assemble and disassemble it. This requires space and, if possible, minimized movement during loading. Although Serrurier lattice systems have been around for a long time, they have only recently been incorporated into budget Dobsonian telescopes and require constant disassembly and reassembly, followed by collimation (a time-consuming operation, but one you get used to with experience).

Sky-Watcher, which has been designing solid-tube Dobsonian telescopes popular with beginners and amateur astronomers for many years, innovated in 2009 with a complete redesign of its instruments. The Chinese-Canadian manufacturer sought to combine the advantages of the fully assembled design of solid tubes with the compact size of open tubes. The concept of a "telescopic telescope" is already a reality (at a still very attractive price) thanks to the FlexTube range.

Based on the principle that " The best instrument is the one you use the most. ", SkyWatcher takes comfort to the next level with the FlexTube range so you don't hesitate for a moment to contemplate the sky and its wonders.

FlexTube: maximum comfort

The FlexTube principle is simple: it's based on a Serrurier lattice design, where three tubes firmly support the secondary mirror cage (which also houses the focuser and finder scope). However, in this case, The tubes are not removable, as they are held in place by a clamping mechanism that allows them to slide. By simply loosening three knobs, the tubes slide down until the instrument folds away. Three screws on the secondary mirror cage secure it to the primary mirror housing. The assembly is much more compact and fits easily, vertically, in the trunk of any car (maximum height of 920 mm for the 305 mm model). With a base of 630 x 740 mm, there's even room for various accessories.

The key aspect of this configuration is maintaining collimation (alignment between the two mirrors). According to the manufacturer, FlexTube telescopes maintain the position of the two optical elements (in particular, the secondary mirror) when folding and unfolding. It's important to note that the alignment remains constant throughout the night, or depending on the position of the optical tube. Therefore, setting up these instruments is incredibly easy. Using the handles (altitude locking knobs), lift the entire telescope (40 kg total for the largest model). Loosen the tube locking knobs (as well as the locking screws). Slide the mirror cage as far as it will go. Finally, tighten the knobs.

Since it doesn't require polar alignment, your telescope is ready for a night of observing full of discoveries. (If you haven't touched the focuser since your last outing, it will already be focused.) In just a few seconds, you'll have completed or avoided the traditional steps: telescope setup, mounting, and collimation. Save time and enjoy unparalleled convenience!

For your information: Check the collimation as a precaution (to ensure optimal performance of your optics), as the primary mirror can shift slightly if you move the telescope while driving (a common issue with all telescopes, generally Dobsonian, Cassegrain, or Newtonian). Use a collimating eyepiece, such as a Cheshire eyepiece, or defocus a bright star.

Mechanical design

Sky-Watcher not only offers telescopes at very competitive prices, but also user-friendly instruments, as demonstrated by the tilting system on all its 150 to 305 mm Dobsonian telescopes. The Chinese-Canadian company has developed and patented (U.S. patent no. 6,940,642) a handle that allows the user to tighten or loosen the optical tube's tilting fork. Depending on the tube's angle and the weight of the focuser accessories (binocular head, eyepieces of different sizes), the observer can increase or decrease the tilt. In this way, the tube is held firmly enough to prevent it from tilting downwards, as can happen with other designs, and it remains free enough to easily point to another part of the sky.

Unlike very inexpensive models or small-diameter Newtonian telescopes, Sky-Watcher Newtonian (Dobsonian) telescopes from 203 to 400 mm feature a parabolic primary mirror The mirrors are polished spherically and then reshaped to achieve a paraboloid form (a more expensive and complex process). This is an essential selection criterion for instruments larger than 130 mm and with a short focal ratio (f/D).

Regarding the material of the primary mirror, The 203/254/305/355/406 mm models are made of Pyrex. This reduces the effects of thermal expansion. In fact, its coefficient of thermal expansion is lower than that of standard glass, which reduces heating time and ensures better image quality. Like the secondary mirror, the primary mirror is coated with layers of titanium dioxide (SiO₂) and quartz (SiO₂) for effective protection.

Important! For safety reasons, the primary mirrors of the Sky-Watcher FlexTube Goto Dobson telescopes (350 mm and 400 mm diameter) are delivered disassembled. They must be reassembled in their cells and the instrument collimated before use. However, the secondary mirrors are delivered mounted on the spider and pre-aligned.

An achromatic finder scope is also included as standard. With a large 50mm diameter and 9x magnification, it reveals objects invisible to smaller finders, greatly simplifying the search. Two eyepieces, with focal lengths of 20mm and 12.5mm (WA 70°), allow you to start with a wide range of magnifications compatible with virtually any objective lens.

Focus for the 355mm and 406mm FlexTube Dobsonian

Focusing is achieved via a dual-speed Crayford focuser. Its 1:10 reduction ratio allows for precise focusing, a significant advantage during high-magnification observations. It can withstand heavy loads. A locking screw located at the bottom of the focuser allows the focus to be maintained regardless of the optical tube's orientation.

A detachable Dobsonian base

Beyond 300 mm, Dobsonian telescopes are difficult to transport on their own (the weight and volume of the smallest component are excessive). However, in the 350 mm and 400 mm diameter models, The panels can be easily detached from the base for transport. The permanent mounting (with Allen screws) is replaced by a removable assembly consisting of knurled screws and inserts. Therefore, the three vertical panels can be easily mounted and detached from the base, while maintaining excellent overall stability.

If you do not wish to disassemble it, the 355mm and 405mm telescopes must be placed in an observatory, on a cart, or moved by at least two people. If you wish to transport a large-diameter instrument alone, we recommend the Sky-Watcher StarGate (Astrolitech) range with a Serrurier lattice structure, which offers diameters 400 mm (which are easier to disassemble and reassemble).

Motorized GoTo system (automatic pointing)

For greater user comfort Sky-Watcher has equipped its range of Dobsonian telescopes with dual-axis motorization (equivalent to a motorized altazimuth mount) and a handheld controller capable of pointing and tracking. Therefore, It is not necessary to know the position of stars or distant deep-sky objects The AZ GOTO Dobson mount automatically moves the instrument to the object you wish to observe.

After calibration (polar alignment), orienting the optical tube towards the north and leveling it, select the mount alignment with one or two stars. More than 42,900 objects, including those from the main catalogs (Messier, NGC, IC, as well as the planets, the Moon and the Sun), are stored in the database For added convenience, the mount is moved quickly using the SynScan hand controller. Easy to use, it helps you quickly point the instrument at any galaxy, nebula, cluster, or object in the solar system. Discover in detail the famous Andromeda Galaxy, the fabulous mantles surrounding the heart of Orion, the Hercules cluster M13, and its core rich with thousands of stars. Saturn, Jupiter, and the Moon are also wonders that can be observed without restrictions.

The display of the date, time, and observation location on the handheld controller, along with The "Tour" function allows you to point the AZ GOTO mount at the most interesting objects throughout the night. Enjoy a guided tour of the sky from your observing location by clicking the "Enter" button after selecting an object from the drop-down list. The ability to track any object eliminates the need for manual repositioning (a handy feature during public observing sessions). The object remains centered in the field of vision This facilitates the discovery of details, especially on planets.

The Sky-Watcher FlexTube GoTo range now includes a built-in WiFi card. which allows you to control the telescope remotely with your smartphone or tablet, without any connecting cable, using the SynScan Pro free application.

Items delivered

• 1 FlexTube Goto 350mm f/4.7 optical tube for Dobson telescope
• 1 Goto Motorized Dobsonian Altazimuth Base for 350mm Telescope
• 1 x 20mm WA 70° eyepiece, 31.75mm body, 82.5x magnification
• 1 WA 70° 12.5mm eyepiece, 31.75mm body, 132x magnification
• 1x 9x50 Right finder
• 1 smartphone adapter
• 1 x 5.5/2.1m power cable with cigarette lighter plug