A Sky-Watcher Dobsonian are alt-azimuth mounted newtonian telescopes design popularized by the amateur astronomer John Dobson
The Sky-Watcher Dobsonian Telescopes have a
"paraboloidal" primary mirror to eliminate spherical aberration and a
four-arm, secondary- mirror bracket with fine supports,
to reduce diffraction spikes and light loss. The design is intended for visually observing "deep sky" objects, a
requirement where the observer needs a large objective diameter (i.e.
light-gathering power) combined with portability for travel to
non-light polluted location. They offers serious aperture with an excellent image quality at a reasonable price.