Are you wanting a good beginner telescope for planet viewing? Many amateurs recommend getting a Dobsonian. Why buy a Dobsonian? There are a few reasons, one being the price. The following looks at Dobsonians and why they are great for beginners wanting to see details of planets and the moon and more.
Are Dobsonian Telescopes Good For Viewing Planets?
A Dobsonian telescope (a reflector type of telescope) will give you pretty decent views of planetary and lunar details if you choose one with an aperture of 6 inches or more.
I cover the recommended aperture size in the different telescope types in my article on what to look for when choosing telescopes for planet viewing.
Why Get A Dobsonian Telescope?
These have a wide field of view and a mount that allows the scope to move in two directions. You will be able to point the scope at the Moon, Mars and other celestial objects and get decent views on a night set for observing.
But then, the main reason you might want to get a Dobsonian telescope is the price.
You can buy a good-sized aperture in a Dobsonian for less than you would any other telescope type.
The bigger the aperture, the more it gathers light, right? The more light-gathering ability the more you will be able to observe the fainter details.
This is what is meant by Dobsonians giving you “the best bang for the buck”.
Why Are Dobsonians Cheaper?
Why are Dobsonians more economical? Dobsonians have a simple design, amounting to a set of optics and a simple mount, and this makes them more economical than other types of telescopes with the same aperture size.
Mirrors cost less than lenses, the optics used in refractors and Cassegrain telescopes, and so the Dobsonians can be made more cheaply than these types of telescopes.
What Is the Difference Between A Dobsonian And A Newtonian?
The optical part of the telescope or OTA (Optical Tube Assembly) in a Dobsonian is like all Newtonian reflectors. Here you have a primary parabolic mirror and a flat secondary mirror in an open-ended tube with a focuser for an eyepiece set on the side.
It works like this: Light enters the tube and is picked up by the primary mirror, which reflects it on so that the light is concentrated onto the smaller secondary mirror (which is flat) and then finally into the eyepiece.
Dobsonian vs Newtonian In General
The mount is basic in a Dobsonian. It is an alt-azimuth type, which allows manual motion in the up/down (Altitude) or east/west (Azimuth) axes. This compares to the equatorial mount of other Newtonians. I explain the difference in my beginner’s guide to stargazing.
The alt-azimuth is the type of mount seen in the GoTo systems, only with a motor.
Downsides of Dobsonians
They need collimation. Best to check out the collimation before use.
For this, you can get a laser collimator or buy a collimating eyepiece.
It may seem daunting at first, but once you get the hang of it, collimating your telescope will be a breeze. I gave a step by step account in my article on collimating a Celestron SCT.
Dobsonians aren’t lightweight (but are transportable). You might take two trips from your vehicle or storage place to set it in place.
What Is The Best Dobsonian?
Amateur astronomers rate the Skywatcher S11600 6-inch as a good starting point for beginner astronomers wanting ‘the best bang for the buck’.
It’s an economical buy. And, a 6-inch aperture in a Dobsonian means you should get useful views of the moon and planets.
Dobsonian Telescope 10 Inch By Skywatcher
This 10 inch Dobsonian is rated a great telescope, made well, with the focuser made of metal rather than plastic. It has great wide-angle eyepieces for eye relief.
It is cheaper than other brands for the same size.
Because it gathers a fair amount of light, you would benefit from getting a moon filter. Also, consider a Barlow lens.
It comes with all the parts and tools to assemble it (assign about half an hour).
Check out the price of the Skywatcher at Amazon — See details.