 The Telescope Nerd- Everything about Telescopes  |
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Looking to Buy a Dobsonian?Thinking about buying a dobsonian? It's a big decision and one that's not made lightly. I have laid out a lot of information here that will help you. -The Telescope Nerd
If you are considering the purchase of a Dobsonian telescope you are making a great decision. This type of telescope offers you remarkable light gathering power at a very reasonable cost. Astronomers know that the most important aspect of any telescope is the size of the primary lens or mirror - the bigger it is the more light you will gather and the more things you will be able to see. Dobsonians are perfect for this because you get maximum lens or mirror size at bargain prices. All of the telescopes I show you in this article are available at amazon.com What is a Dobsonian Telescope?A dobsonian telescope is a Newtonian style reflector telescope that uses the traditional optical system of a newtonian but varies radically in its approach to the mount on which the telescope tube is placed. A more conventional type of newtonian telescope is mounted on an equatorial mount like the one in the picture here:
Newtonian telescope on an equatorial mount The Tube assembly is a typical newtonian reflector. And the mount that it is on is an equatorial on a pedestal mount. This type of mount is well suited for astronomy in that it aligns up with the earths rotation and it only takes a single motion to follow objects across the sky. It is also well suited for a motor that will automatically move the scope and follow objects in the sky which is great for astrophotography.
A Dobsonian Telescope This shows a typical dobsonian. Notice how the tube assembly is pretty much the same as the newtonian shown above. The change is in the mount of the scope at the bottom. This simplified mount makes it very easy to set it up and to use it. You simply move the scope gently around to point at objects.
That change in the mount is what makes a dobsonian different and what makes it easy to use and much more affordable. When you use a system like this you are able to get a much larger mirror on the scope for a much lower cost. It is much more user friendly and beginner astronomers take to it very quickly. John Dobson is the creator of the Dobsonian telescope. He is a champion of amateur astronomy and has had many achievements in astronomy over many decades. He is also the co-founder of the San Francisco Sidewalk Astronomers Club. Some of the benefits of a Dobsonian Telescope Light gathering power vs. cost - First off, as I mentioned you get stunning light gathering ability at a very reasonable cost. A typical equatorial mount telescope of the same size would cost twice as much and if you were to buy a Schmidt-Cassegrain folded optics telescope of the same aperture you would easily pay four times the cost of a Dobsonian. And if you were to get a refractor of the same aperture the cost goes up to around ten times. Ease of setup - This type of telescope is extemely easy to setup and for most models you simply place the tube on the mount and you are done. So if you are unfamiliar with equatorial mounts or are not mechanically inclined a dob is a good choice for you. Simplicity of use - Pretty much a point and look kind of telescope. It easily rotates and turns to any location you want with no fuss. Avid Amateur Astronomers love them - Because for the cost you can get enormous light gathering power (big mirrors) which means you can really get some fantastic viewing. Trade-offs when buying a Dobsonian I probably don't have to tell you that there are trade offs but there always are when you purchase anything. There are some deficiencies with Dobsonians that you will want to consider before you buy. Not suited for astrophotography - Most dobsonians don't track objects across the sky which means you can't get long exposures and deep space photos. There are exceptions to this rule and Orion does make a dobsonion with computerized tracking control but this will cost you around an extra two hundred and fifty dollars. If you really think you want to put the time and effort into astrophotography you might want to overlook the dobsonian and get another type of scope. They tend to be a bit heavy - The weight of them is similiar to traditional newtonian telescopes but significantly more than the folded optic type scopes that can be placed in a suitcase and carried around. Of course the folded optic types are much more expensive. Once initial assembly is done they come in two halves - the tube and the mount. And each half typically has a handle for carrying. Now let's look at the different sizes of DobsoniansAmazon.com has Dobsonians from Orion and Meade with mirrors that range from 4 1/2 inches in width to 12 inches in width. The cost (generally and subject to change) goes from a little over two hundred dollars to about a thousand dollars. So let's take a look at them. I will point out the pros and cons of each so you can make the decision that is right for you. 4 1/2 mirror telescope
The manufacturer of this scope is Meade and they make top quality scopes. You will be satisfied with the quality. But, I do have some recommendations about the size of the scope. We talked about the biggest advantage of a dobsonian is the fact that you can get much bigger mirrors and a lot of light gathering power from them. This is a small telescope so it goes a bit contrary to what dobs are all about. But it will be very easy to maneuver and use if this is a concern. If you are really concerned about price and on a tight budget this could be a good choice for you. It's a quality entry level telescope. If you already own a telescope I don't recommend this one though. 6 inch mirror telescopes Now with the increase in mirror size we are starting to get more light gathering power out of the scope. This is more in the realm of achieving what you can get out of a dobsonian telescope yet it is still small enough and light enough to be comfortable to handle and move.
This scope is made by Orion and they are a reputable maker of telescopes. It is made so you can add the optional Intelliscope finder that will help you find thousands of object in the sky. Although I don't really recommend that option. It is a bit much for this size scope. And it does bring the overall cost up quite a bit. I recommend the Intelliscope if you are going to the 8" scope or larger. Orion IntelliScope Computerized Object Locator Give your IntelliScope Dob a brain! Simply plug the Computerized Object Locator into the base of any SkyQuest XT IntelliScope and you're all set to locate and view any of 14,000 celestial objects. You just select an object from the user-friendly menu buttons, then move the telescope in the direction of the guide arrows on the LCD screen.
Galileo 1300mmx160mm Dobsonian Telescope 8 Inch Mirror Telescopes I consider this size telescope to be the absolute best value in the range of Dobsonians - particularly if you are only an enthusiast of astronomy or a beginner. The mirror size is substantial and it will give you an enormous difference in viewing over the 6 inch. This is the type and size scope that could give you a lifetime of enjoyment. If you can afford it I recommend it.
Orion SkyQuest XT8 Classic Telescope with Bonus Accessory Pack Crayford-Style Focuser Our classic XT8 isn't just great bang for the buck, it's a veritable explosion of telescope value. It combines powerful parabolic optics with the ultimate in mechanical stability. The SkyQuest XT8 features an 8" parabolic primary mirror that will tease out detail in nebulas, resolve stars in globular clusters, and reveal subtle structure in galaxies. The enameled steel optical tube sports an upgraded 2" Crayford-style focuser that accepts both 2" and 1.25" eyepieces. The tube moves effortlessly on Teflon/UHMW bearings for point-and-view simplicity. Comes complete with navigation knob, two 1.25" Sirius Plossl eyepieces, eyepiece rack, quick-collimation cap, and hard dust cap. The one shown above is without the Intelliscope locator and you can buy the two together as a package and save money: Orion SkyQuest XT8 IntelliScope Dobsonian Telescope with Object Locator As an alternative you may want to consider an 8" from another company. This telescope has gotten some good reviews and is competitive in price. Zhumell DOB-8 8-inch Dobsonian Reflector Telescope 10 Inch Mirror Dobsonians Now we are starting to talk telescopes. This size scope is for the serious beginner or the amateur who is familiar with the night sky. Normally this size scope is not what you get as a first scope. But with Dobsonians you can stretch this one into that category if you are an ambitious beginner. This thing is going to bring the night sky alive for you with breathtaking views of thousands of objects. The first scope I show here is the Meade and it is without the Intelliscope option but I recommend if you are going to get this size telescope you get it with the Intelliscope so you can get the maximum potential out of it.
Orion SkyQuest XT10 IntelliScope Dobsonian Telescope w/o Object Locator Orion SkyQuest XT10 IntelliScope Dobsonian Telescope with Object Locator
If you are concerned about the weight and handling of the telescope. Which can be a concern when moving it, getting it out of the house and into the car etc. you might want to consider one of Meades Truss-tube telescopes. They are of the same quality but designed to be lighter and easier to handle.
10" LightBridge Truss-Tube Dobsonian (Deluxe)
These unique lightweight large-aperture telescopes break down and set up in minutes.
If you want the absolute biggest telescope aperture you can get for the absolute lowest price no frills yet high quality optics you should take a look at the Celestron line of dobsonians. This ten inch is a marvel and an incredible bargain. Celestron is every bit as good as Meade. Nice way to get absolute enormous light gathering out of a small price.
Celestron StarHopper 10 Telescope - 10110
12 Inch Mirror Dobsonians Well, this is it. If you are an amateur astronomer you are no doubt going to drool over this one. It's a monster and it is a marvel of the world we live in. What would Galileo have said after looking through this scope? You are going to spend a lifetime of amazement with something like this.
12" LightBridge Truss-Tube Dobsonian (Deluxe)
Some Further Resources All of the telescopes I have shown n this article are available at amazon.com
The Dobsonian Telescope: A Practical Manual for Building Large Aperture Telescopes This book tells how you can build a state-of-the-art Dobsonian telescope using readily available materials and supplies. Every step of construction is detailedin photographs and diagrams, and the underlying ideas are carefully explained.
The Backyard Astronomer's Guide Despite the book's title, there is very little about astronomy here, i.e., lists of constellations, star charts, night sky maps, or details about planets, stars, and galaxies. However, there is a wealth of information about the equipment used in astronomy, including prices, consumer-type information, advice on when to use and when not to use binoculars, telescopes, cameras, film, lenses, filters, and other items for the amateur astronomer. Four chapters, though, concern the observation of the solar system and deep space objects. There are also several chapters discussing the photographing of all types of astronomical phenomena. Though cost may deter small-to-medium-sized libraries, there is much information here for the experienced amateur, and some useful information for the beginner as well
Starry Night Complete Space&Astronomy Pack
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Telescope Stuff
Articles: A guide to buying a Dobsonian Telescope A tour through the universe for casual or first time astronomers Telescopes are not just for nerds! Understanding Magnification and Telescopes or How high can a telescope go? Why is the eyepiece on the side of some telescopes? Understanding the parts of a reflector telescope The difference in performance, use, and cost between reflector and refractor telescopes You don't know much about telescopes but want to buy your first one? Here is my recommendation Make and use your own telescope for less than twenty bucks with this easy kit Astronomy with Binoculars a bit about what to know The biggest challenge to telescope users is overcome with Meade Telescopes
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Orion SkyQuest XT4.5 Dobsonian Reflector Telescope
Orion SkyQuest XT6 IntelliScope Dobsonian Telescope w/o Object Locator
Looking over the statistics and the pictures my opinion is that this is a telescope of the same quality as Meade or Celestron but I can't really know without actually using one. One drawback is that it seems that this scope doesn't come with any eyepieces which is a price consideration. 
