Telescopes | Astronomy | Cosmos



How Big Should Your Telescope Be?

There is a persistent myth that larger telescopes produce better magnification. This is not strictly true. Magnification depends on the lenses the telescope is fitted with, and with the correct eyepieces, even a small telescope can produce a lot of magnification. If so, then what is the point of a larger telescope? Simply put, the size of a telescope’s lens or the telescope’s mirror determines the amount of light it can collect. This is usually measured in inches, and will often be part of the telescope’s description.

The larger the lens, the more light a telescope can collect. The difference becomes most apparent at higher magnification levels: for example, at 120x magnification, a ten inch telescope will reveal many more objects which you might not be able to see at the same magnification level but with a three inch telescope. In addition, the image produced by the ten inch telescope will be brighter and clearer, because the larger lens can collect more light. In general, a large telescope will tend to outperform a small telescope, though superior optical quality and special features may allow the reverse to be true in some cases.

So – why shouldn’t you buy a larger telescope? For one, a larger telescope weighs more, costs more, is bulkier, and will generally be more difficult to use without a specialized telescope mount, which costs even more. More to the point, if a telescope is difficult to use, then odds are, it won’t be used – and that makes the entire telescope a wasted investment. In general, it’s always best to consider your own needs and resources before purchasing a telescope. Most amateur astronomy can be done without excessive magnification demands – 200x is sufficient, and 350x is almost as high as you can go before the law of diminishing returns makes purchasing a more powerful telescope less worthwhile. The actual size of the telescope does not need to be overly large as well – depending on your usage needs, a size of four to six inches will more than likely be enough for you.

It’s always helpful to ask a more experienced person or a dealer you can trust about the kind of telescope you need. While dealers want to make your money, they generally also want repeat business (especially if you choose to upgrade, they want you to do it through them), and so in general, they’ll want to treat you well. Most dealers will also be familiar with their own stock, so they can explain the ins and outs of their equipment to you.

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