A Dobsonian telescope is an alt-azimuth mounted Newtonian telescope design popularized by John Dobson starting in the 1960s 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. This type of observation requires a large objective diameter (i.e. light-gathering power) of relatively short focal length and portability for travel to relatively less light polluted locations.