When choosing a telescope, you have many decisions to make. There is no one best scope for everything, so you have to decide between higher magnification or wider fields of view, aperture versus price and portability, tracking ability versus setup time and ease of use, etc. This section will help you work through those decisions. If you want to learn more about the types of scopes mentioned here, please refer to the Intro to Telescopes section.
The first decision is what you want to observe. Where do your main interests lie? Are you primarily interested in planets? The moon? The sun? Galaxies and nebulas? In other words, are you more interested in objects with fine detail, or fainter, more diffuse objects that need to be teased out of the background sky? If you don't know what you want, then go back to the getting started page. There is no point in buying a scope unless you know what you want to look at. That may sound harsh, but I want you to be happy with your investment - not disappointed!
The second decision - or rather set of decisions - is where will you store it, where will you use it, and how will you transport it? these questions, probably more than anything, will determine the size of your new telescope.
The third decision is how much you are willing to spend. At this point you can ball-park a figure, but be prepared to be a little flexible until you have seen what is available.
Now let's work through the decision making process:
Rule # 1: Aperture wins. The larger the aperture, the more you are able to see, but also the more expensive the scope.
Rule # 2: Optical quality is important. This should be obvious, but department stores and toy stores still sell junk scopes by the thousands.
Rule # 3: Aperture wins. See rule # 1
Rule # 4: Big scopes are harder to move, and fancy scopes take longer to set up. These are hindrances to rule #1
If your main goal is to see brighter, detailed objects such as the moon and planets, then a smaller aperture scope with a longer focal ratio is a reasonable choice. A refractor with an aperture in the range of 80-90mm is fine for a first scope for lunar and planetary observing. A focal ratio of f/10 or more will give more pleasing detail with less chromatic aberration. A Maksutov-Cassegrain of 90-100mm aperture at f/12-f/15 will give similar views in a more compact package.
If you are interested in fainter objects, such as galaxies and nebulas (nebulae?) you will want more aperture, at least 130-150mm, but more is better. In the larger aperture scopes, a Newtonian reflector will be considerably less expensive than a refractor or catadioptric design.
When it comes to selecting a type of mount, the intended use is also important. If you are planning on looking for fine detail at higher magnifications, you have to consider that the motion of objects across the sky (actually the Earth's rotation) will be magnified by an equal amount. At 200x, an object may drift out of the field of view of a stationary scope in less than a minute, so an equatorial mount may be desirable for easier tracking. At lower magnifications, it is less of an issue, and an altazimuth mount should suffice.
Having gone through this process myself not long ago, I know the agony and indecision you may be facing, so let me cut to the chase. My recommendation for a best, all-around scope for deep-sky, lunar and even planetary observing is a 200 mm (8") Newtonian reflector on a Dobsonian mount. This combination will give you maximum bang for your buck - the upgrade from a 6" is not huge, but the extra cost for a 10" is a big jump. The Dobsonian mount is inexpensive, and yet sturdy. This type of scope is sold by a number of manufacturers, including Skywatcher, Orion, Celestron, Meade, Discovery, Hardin Optical, and others. Two of the main suppliers for these companies are Synta of China and Guan Sheng of Taiwan. It has been reported that, in general, the Guan Sheng Mirrors have a slight advantage optically, but the Synta mirrors are also respectable - I'm happy with mine.
If you don't feel quite ready for that level of commitment, a 6" Dobsonian is also a reasonable choice. An even cheaper alternative, as a child's scope or casual use instrument, is the little Starblast from Orion. This is a diminutive 114mm f/4.5 reflector which is reported to have excellent optics for its price. The only drawback is that it needs to be placed on a table to be used, unless you want to use it while you are sitting on the ground (not fun if there is dew on the grass!).
For equatorially mounted scopes, there is a dilemma. The lightest mount that is worthwhile is the EQ3 style. Anything smaller, such as the EQ2, tends to be less well constructed, more wobbly, and more awkward to use. The EQ3 is of course more expensive, and considerably heavier. But if you plan on purchasing any other telescopes, the same mount can be used, allowing you to purchase the optical tube only. Consider it an investment... Most of the entry level EQ-mounted scopes come with an EQ2 mount. If you are serious about the hobby (and if you have read this far, I hope you are), find out about upgrading to an EQ3 - which will probably cost a premium of about $100 Canadian. In the Bang-for-buck department, I would recommend a 130mm f/5 Newtonian (make sure it has a parabolic mirror!), or a 90mm f/10 refractor. Another option, though at a slightly higher price, is a 102mm Maksutov, such as the Skywatcher or Orion Starmax. The 102mm is only slightly more than the 90mm model, but considerably less expensive than the 127mm. Again, an EQ3 is recommended, though the mount would weight considerably more than the little scope!
Short Tubes: There are a number of small, short-tube refractors on the market, and many (though not all) of these are reported to have respectable optics. An 80mm f/5 is compact and easy to use, but I would not recommend this style for a first scope. The short focal ratio leads to increased chromatic aberration, and high power views will be disappointing. As a wide field scope (sometimes called a "rich field" scope) this style works well, but the small aperture will not show faint objects clearly. As a second scope - once you know what to expect and what to look for - they can be a lot of fun. Stick to a wider aperture and/or longer focal ratio for a first scope.
Used Scopes: There are many excellent bargains to be had in the used scope market, but also many traps for the unwary. Unless you know either the scope or the vendor personally, or know someone who can help you choose widely, I would recommend buying a scope new from a reputable dealer. Once you are familiar with the ins and outs of telescope use, and what different models are capable of, and which makes are lemons, then you can buy used with some confidence.
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