Dobsonian

A Dobsonian telescope is an altazimuth-mounted Newtonian telescope design popularized by John Dobson starting in the 1960s and credited with vastly increasing the size of telescopes available to amateur astronomers. Dobson's telescopes featured a simplified mechanical design that was easy to manufacture from readily available components to create a large, portable, low-cost telescope. The design is optimized for visually observing faint, deep-sky objects such as nebulae and galaxies. This type of observation requires a large objectivediameter (i.e. light-gathering power) of relatively short focal length and portability for travel to relatively less light-polluted locations