Dobsonian telescope

This type of observation requires a large objective diameter (i.e. light-gathering power) of relatively short focal length and portability for travel to less light-polluted locations.

[citation needed] John Dobson, credited as having invented this design in 1965,[5] pointed out that "for hundreds of years, wars were fought using cannon on 'Dobsonian' mounts".

Dobson identified the characteristic features of the design as lightweight objective mirrors made from porthole glass, and mountings constructed from plywood, Teflon strips and other low-cost materials.

[6] Dobson combined all these innovations in a design focused towards one goal: building a very large, inexpensive, easy to use, portable[7] telescope, one that could bring deep-sky astronomy to the masses.

Because "deep sky" observing often requires travel to dark locations away from city lights, the design benefits from being more compact, portable, and rugged than standard large Newtonian telescopes of times past, which typically utilized massive German equatorial mounts.

Designers started coming up with disassembleable or collapsible variants that could be brought to the site with a small SUV, hatchback, or even a sedan.

The poles are held in place by quick-disconnecting clamps which allow the entire telescope to be easily broken down into its smaller components, facilitating their transport by vehicle or other means to an observing site.

In the 1980s, they helped popularize the design with "Odyssey" models of various sizes, with tubes made of Sonotube and following Dobson's original concept of simplicity.

[28] These low-volume builders offer premium objective mirrors, high-end materials and custom craftmanship, as well as optional computer controlled GoTo systems.

A massive 36 inch (914 mm) aperture Hybrid model from New Moon Telescopes was displayed at the 2018 Northeast Astronomy Forum.

[31] In 2019, a huge 50 inch (1270 mm) aperture folded Newtonian from Canadian based Optiques Fullum was installed in New Jersey.

The result has been a proliferation of larger telescopes which would have been expensive to build or buy, and unwieldy to operate, using "traditional" construction methods.

It also makes possible searches for new, faint objects such as novae / supernovae in local galaxies, and comets (for reports to the Central Bureau for Astronomical Telegrams).