Sky-Watcher Quattro 200p f4 10238

“The Quattro’s tube is lined with a set of nine internal baffle rings. Their main purpose is to cut down on stray light entering the telescope tube, helping to improve image contrast, but they also lend a bit of extra stability to the tube structure….The Quattro-8S is fitted with a Crayford-style focuser that performed well. It has tension adjustment, focus-lock and a 10:1 dual-speed fine focusing option, and also comes with a 2-inch fitting that has a T-thread on its external side. This allows a good connection to be made between scope and camera with the right adaptor ring….Visually, the Pleiades looked like diamonds hanging in space, with a hint of nebulosity visible around the brightest star Merope. The stars were generally crisp and sharp, with good colour on show. The scope is superb for imaging too, delivering shots that appeared to have higher contrast t han the other scopes on test.”
BBC Sky At Night Magazine (Quattro-8S model)

Supplied with a set of tube rings, 45mm dovetail bar, piggyback camera adaptor and a 9×50 fully multi-coated finderscope with crosshair reticle. 1.25” & 2” eyepiece adaptors are included allowing virtually any standard 1.25” or 2” eyepiece to be used. Equipped with a 2″ Dual-Speed Linear Power Focuser that utilises 4 precision ball bearings to support the drawtube and provides great stability and zero image shift while supporting a heavy eyepiece or camera. Moving the drawtube by the roller rather than a rack and pinion ensures exceptionally smooth operation, great feel and precise adjustability. The dual-speed feature has a second focus knob that has a 10:1 speed reduction to provide the super-fine adjustments even the most demanding users can appreciate.

The heart of any Newtonian telescope is in the quality of its mirror optics. The accuracy of the figure, the material they are made from and the coatings applied all play an important part. Sky-Watcher’s prowess and reputation for commercial mirror making is well known and one of the jewels in its crown. Sky-Watcher has demonstrated its unwavering ability to produce telescope mirrors of consistent high quality over decades. Parabolic (or Paraboloidal) mirrors are a complex shape so need to be well made to provide the high performance expected of them. A properly figured parabolic primary mirror will eliminate spherical aberrations by bringing the light rays to the same focal point. Sky-Watcher’s diffraction-limited parabolic primary mirrors will produce sharp, contrasty images that are full of detail.

The Quattro 200P primary & secondary mirrors are made from special Low-Expansion Borosilicate glass, similar to Pyrex. It has an exceptionally low coefficient of thermal expansion compared to regular glass types. In practice this means a quicker cool-down time to reach thermal equilibrium, and during the cool-down process the mirrors will maintain a better shape, reducing distortions, allowing you to start observing sooner.

The secondary mirror is held in place by four specially designed 0.5mm thin spider vane supports which are extremely rigid when tensioned. They serve to minimise obstruction to the light path, allowing the passage of more precious photons and keeping diffraction spikes to an absolute minimum.

Both primary and secondary mirrors are finished with Sky-Watcher’s RAQ™ Radiant Aluminium Quartz coatings, which include layers of aluminium, tantalum pentoxide and silicon dioxide for a brilliant, highly durable finish with 94% reflectivity that will last for years.

The colour scheme is not just an aesthetic. The OTA is tastefully finished in Sky-Watcher’s proprietary Black Diamond flecked metallic paintwork and features, by design, complementary contrasting white painted surfaces. The white surfaces are a highly practical feature for providing more visibility, which can help prevent your expensive and carefully aligned telescope from being knocked accidentally in the dark.

With a tube weight of 9kg, this OTA would be a good match for the Sky-Watcher AZ-EQ5 Pro, HEQ5 Pro, HEQ5-R Pro, EQ6-R Pro, AZ-EQ6 Pro Wave-100i or Wave-150i mountings

8” f/4 Newtonian OTA designed for wide-field imaging. This uses a parabolic primary mirror so at f/4 there will be a noticeable amount of off-axis coma. Use the Baader or Skywatcher coma corrector for images free of coma. These telescopes can also be used visually, but bear in mind that as they are optimised for wide-field imaging, the secondary will be a little larger to reduce vignetting. Its performance visually will likely be slightly inferior to a standard f/5 visual Newtonian. With the coma corrector these instruments are capable of excellent photographic results. The carbon fibre tube assembly is designed so that there is no linear movement of the tube length or width as it cools. It does not expand or contract during temperature change like metals. This means that during a long exposure, the image on the chip will remain in sharp focus. Bear in mind that carbon fibre does not lose heat very quickly, so although the tube will not move, it will radiate for longer than aluminium or thin ferrous metal. A carbon fibre tube needs to be left to cool for longer, prior to serious imaging.

Budget for a good quality coma corrector – essential. Preferably, one that does not alter the focal length of the telescope. Construct a matt black dewshield of some 300mm in length. This will help to draw cool air up through the telescope passively, and also decrease light reflections around the secondary position. Keep these telescopes in perfect collimation. Even slight mis-alignment in an f/4 Newtonian noticeably reduces image quality.