As telescope technology advances, the telescopes available to the average backyard astronomer is getting better all the time. This has led to an explosion of new Dobsonian telescopes hitting the market in recent years. If you have done any kind of research into a new telescope you have definitely come across one of these types of telescope.
For anyone who knows that there are only two kinds of telescopes available to the general public, refractor and reflector telescopes, this third kind of telescope might be confusing. Is there a new kind of telescope that was invented recently that you missed? Not quite.
What is a Dobsonian telescope and what are they for?
The answer is simpler than you think and may surprise you.
Key Components of a Dobsonian Telescope
Dobsonian telescopes are a special kind of reflector telescope that has a set of distinct characteristics that differentiate them from other telescopes. They are not a new kind of telescope in terms of optics, they are a modified Newtonian reflector design.
Dobsonian telescopes are large aperture Newtonian reflectors. At their very smallest, Dobsonians have a minimum aperture size of 5”. However, many Dobsonians run from 6” in diameter all the way up to 12” or even 14”. These are truly massive telescopes compared to normal reflector designs.
These ever-growing sizes have driven necessary adaptations to the traditional telescope designs. These massive apertures have ballooned in size until the optical tubes now weigh anywhere from 30lbs to 60lbs. Oldschool tripods just won’t cut it for telescopes of this size.
Instead, Dobsonian telescopes come with large, heavy, flat bottomed bases that hold up the large optical tubes. These bases act as both a counterweight to the heavy aperture as well as a sturdy base on which the whole array sits.
This combination of large, heavy base plus a wide aperture reflector is what makes a Dobsonian a Dobsonian.
This setup is named for John Dobson, an astronomer who began popularizing this design in the 1960s. He wanted amateur astronomers to have access to the larger telescopes that were becoming available at the time. To compensate, he designed and created his now famous base that supports truly large backyard telescopes.
Next time you see a Dobsonian telescope, remember, they are just large bodied, wide aperture reflectors with a specialized base to support them. They are never refractors and they will never be seen on a tripod.
That’s all well and good but what are they for?
What Are Dobsonians Good For?
The main draw of a Dobsonian telescope is the larger than normal apertures that they can support. If you think that regular 3” or 4” reflectors are too small for your ambitions, you might want to take a look at a Dobsonian.
Their super aperture sizes open up completely new avenues of stargazing. The bigger apertures lead to better light gathering capabilities which leads to new and distant objects that can be found and studied.
If you are interested in deep space stargazing or using astronomy to find faint and distant objects that most people will never see, a Dobsonian will be the telescope for you. These scopes will be seeing things that don’t have names, just numerical catalog designations. If that thought excites you, you will want to look into these telescopes.
Their wide angled apertures mean that these telescopes usually have a low focal ratio which leads to wider, less detailed shots than a similar refractor telescope or a telescope with a high focal ratio. This is perfect for the faint and distant objects these telescopes excel at.
It will not be able to efficiently scope a binary star or planet but it can see distant galaxies and nebulas that other, smaller, reflectors just aren’t able to view.
What Are Dobsonians Bad For?
Right off the bat, Dobsonian telescopes are not portable. Technically, you can disassemble them and detach the tube from the base but the process can be complicated, and moving such a large reflector tube is guaranteed to give you calibration issues down the road.
If you are looking for a portable telescope, you are not looking for a Dobsonian. Their size and weight make them poor choices for a grab and go scope.
Dobsonians are not great at seeing small bright objects like planets, comets and single stars. If those types of near-Earth objects are what you are most interested in, you are better suited to a smaller telescope.
These telescopes are usually more expensive than other scopes as well. Their large apertures and heavy bases increase the material costs so that even the smaller Dobsonians are usually a chunk more expensive than smaller more basic telescopes.
Is A Dobsonian Telescope Right For Me?
If you are interested in deep space, like really deep space, you are eventually going to be drawn to a Dobsonian telescope. They offer some truly stunning views of deep space that you just can’t get anywhere else. There are massive 12” diameter scopes that can see exponentially farther than any other backyard telescope available on the market today. If that kind of long view distance appeals to you, then a Dobsonian is going to be a necessity someday.
If you are not interested in deep space and are more interested in traditional sights like Mars, Alpha Centauri, and comets, then you do not need to invest in a Dobsonian telescope. Also, if you are a complete beginner you might find a Dobsonian a little too intimidating to start.
Peering into deep space and getting a bead on super distant objects takes some experience and knowledge of how reflector telescopes work. They also can require collimation and calibration which, on mirrors of these sizes, can be offputting for brand new astronomers.
If the large aperture sizes excite you and do not intimidate and your budget can afford the money, then a Dobsonian can be an excellent tool for backyard astronomy. If you choose the right Dobsonian, it can be a telescope that lasts you for years without any issues.