A Newtonian telescope on a simple box base that swings up and down and turns round, popularised by John Dobson in the 1960s and 1970s. You nudge it by hand to follow objects. Quick to set up and very steady, it gives a beginner the largest aperture.
ToolsNewtonian calculator
Related terms
- Newtonian telescope
The telescope invented by Isaac Newton in 1668: a concave primary mirror at the bottom of the tube and a small flat mirror at 45° that sends the image out to the side, near the top. With no lenses it is free of chromatic aberration and offers a lot of aperture for its simplicity. It needs regular collimation.
- Alt-azimuth mount
A mount with two axes, one vertical (azimuth) and one horizontal (altitude), like a photo tripod. Intuitive and with no polar alignment, it needs both axes moved to follow an object. In long-exposure imaging the field rotates as the minutes pass.
- Equatorial platform
A motorised base slipped under a Dobsonian, whose motion mimics an equatorial mount for about an hour. The telescope then follows objects on its own, which makes high power and sharing the view much easier. It is then reset to its starting point.
- Push-to
A set of encoders on the axes of an unmotorised telescope, often a Dobsonian, linked to a handset or phone. The screen shows which way to push the tube to reach the chosen object. You keep the simplicity of a manual mount, with help to find things.
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