In all of the above you may have noticed that I didn’t talk about magnification power, which is typically what is promoted for lesser quality telescopes. The critical item in any telescope is it’s light gathering ability, which is directly related to its aperture. In refractors it means the larger the objective lens, or in reflectors, the larger the primary mirror, which allows more light to be collected and focused to your eye, providing a brighter, higher contrast image and this allows the observer to glean more detail about the object they are viewing. The magnification comes through the eyepiece, which can be changed to accommodate what you are looking at and what you want to see. The higher the magnification, the larger the image you will see, but it will be dimmer and not necessarily the sharpest, most detailed image. Higher magnifications also mean you’re you are looking at a smaller piece of the sky, which makes tracking the object more difficult. Any defects in the optical train (and this includes all the jiggles the atmosphere introduces in your image!) will become more evident as you increase the magnification, which causes the image quality to decrease. Low magnification gives you a wider field of view and reduces the tracking issues. Don’t think that lower magnification means boring objects to look at; there are many amazing objects that will astound you, like open clusters, nebula, and the Andromeda Galaxy (M31). Check out the article on “What You Can See with Your New Telescope" for more information.
So, which one to choose?
Now that you have an idea of what is out there, which one is best for you?
Consider what your experience with astronomy is. If you are just beginning to explore the night sky you can begin very simply with your eyes, and a chart of the night sky. This will allow you to become familiar with the constellations, planets and other objects that are visible to the naked eye. A step above this is practising astronomy with binoculars that will allow you to see much more (typically about 50 times more). If you feel that you are ready to get a telescope and want to get into it gradually then the Dobsonians provide a great choice to get started—low cost and great optics. You will learn the night sky, where and how to find the celestial objects of interest and develop an intuitive feel for navigating the cosmos—something that you won’t get with a computerized telescope or “GoTo" scope.
If you are sure that you want to get into the field of astrophotography or want to hook up your scope to your computer then you will need to get a scope that has an electronic/computerized drive system and you can look at any of the telescopes discussed, it depends on the objects you want to photograph (i.e. planets or deep space objects) and how much you have to spend. These scopes will be heavier because of the substantial mounts needed to stabilize the scope for the long term exposures and therefore will be more expensive and take more time to move and set up.
What ever you decide to buy, make sure that you purchase from a reputable supplier and do some research on what you are buying. Check out online user reviews and the sites for Astronomy and Sky and Telescope magazines for equipment reviews. Do not be swayed by magnification, remember, it is the light gathering ability that will give you a better image – larger mirrors on reflectors and lenses on refractors. With regards to the larger aperture scopes, they will get physically bigger and heavier, so make sure that you are not buying something so big that you don't want to haul it outside and set it up. Buying the best scope in the world is a waste if you are not inclined to use it. Stay away from the bargain store specials and pay a bit more for quality optics and construction; in the long run you will be much happier with your decision and you can start making plans for your backyard observatory—but that’s another article!