Sky-Watcher 200mm Dobsonian Telescope

Sky-Watcher Dobsonian telescope with the best diameter/price ratio

• Ideal instrument to make the most of deep sky observation
• Versatile planetarium (Moon, planets) and deep sky (galaxies, nebulae)
• Easily transportable by a single person (tube + base)

Everything you need to know about the Sky-Watcher 203mm f/6 Dobsonian telescope

In recent years, the Dobson fever has increasingly invaded amateur astronomers aware that the strongest sensations are felt with large diameter telescopes. In fact, observation of the planets is limited to Jupiter, Mars, Saturn (and the Moon), while clusters, nebulae and galaxies are counted in the hundreds on a 200mm instrument (see thousands for the largest diameters under a dark sky). Without motor or electronics, the Dobsonians are in fact the instruments that provide the most light, on a given budget, compared to any other type of instrument (mainly motorized and Go-To). Sky-Watcher designs solid tube dobsonians appreciated by beginners and hobbyists for many years across a range extending from 150mm to 305mm.

Hobbyists will appreciate the 200 and 254mm because they can show many more objects in greater detail. They fall into the range of instruments that can be kept for many years before reaching their limit. . It is also possible to combine them with O-III or UHC filters to see the most beautiful nebulae from a different perspective (more contrast, less light pollution). The 305mm offers excellent views of thousands of objects (NGC/Messier catalogues). Nebulae, globular clusters and galaxies will be easily accessible.

For visual observation enthusiasts, this is the best price/performance ratio! Enjoy a "real" telescope without delay. Guaranteed excitement, minimal investment!

Optical design

Newton's design offers several advantages on other families of instruments (Cassegrain receivers and telescopes). Firstly, mirrors are cheaper to manufacture for an equal diameter and their focal ratio is generally very low. Then you benefit from a very attractive quote for a brilliant telescope which provides an almost coma-free field in the 200mm model (the 254 and 305mm with their short focal ratio can be supplemented with a coma corrector). The central obstruction is weaker than Cassegrain type telescopes, if collimation (mirror adjustment) is well respected, the image quality is good in planetarium. The Dobsonian mount also greatly reduces the price of this telescope compared to motorized equatorial mounts.

Unlike very cheaply made or small diameter Newtonian telescopes, the 150, 203, 254 and 305 mm Sky-Watchers Newton (Dobson) have a parabolic primary mirror . The mirrors are polished spherically and then trimmed to achieve a paraboloid shape (more expensive and difficult to obtain). This is an essential selection criterion for instruments above 130 mm and with a short f/D .

Mechanical concept

Sky-Watcher not only offers telescopes at very advantageous prices, but also easy-to-use instruments, as demonstrated by the tilt system that is installed on all Dobsonians from 150 to 305 mm. In fact, the Chinese-Canadian firm has developed and patented (US Patent No. 6,940,642) a handle that allows you to tighten or loosen the fork on the optical tube. Thus, depending on the inclination of the tube and the weight of the accessories present in the eyepiece holder (binocular head, eyepieces of different angles), the observer can increase or decrease the friction. The tube is then supported enough not to tilt downwards. as with other constructions and free enough to be easily oriented towards another place in the sky.

Focusing is achieved through a bi-flow focuser . A 31.75mm adapter is supplied as standard to use eyepieces of the same format from the 50.8mm output. A clamping screw located on the top of the focuser maintains focus according to the orientation of the optical tube. A 9x50 achromatic viewfinder is also supplied as standard. on its support. With a large diameter of 50 mm for 9x magnification, it reveals objects invisible to researchers of smaller dimensions.

Regarding the material used for the primary mirror, 254mm and 305mm Dobsonians benefit from Pyrex glass which has the effect of reducing the effects of expansion due to thermal changes. In fact, its thermal expansion coefficient is lower than standard glass, which reduces its warm-up time and guarantees better image quality.

The kit includes:

• 1 Newton Sky-Watcher 203mm f/6 optical tube
• 1 Dobsonian azimuthal mount
• 2 31.75mm fluid eyepieces: Super 10mm and Super 25mm
• 1 9x50 finder

Specifications