How to Buy a Telescope

The most important thing to know when buying a telescope is power is NOT important. No matter what the manufacturers claim, pay no attention to their boasts of power! In fact, if they do advertise by power alone, you can pretty much assume that it is not a telescope worth buying. Before you start looking for a telescope, ask yourself these questions:

1. What do I want to use the telescope for?

    land viewing?

    space?

    deep space?

    all of the above?

2. How will I use this telescope?

    will I leave it in one spot?

    will I travel with it?

    is size of the scope important?

3. How much money am I willing to spend?

The important things to think about are the size of the aperture, the type of telescope and what you would like to use it for. The aperture size will determine the amount of light gathered by the telescope and determine the clarity of the object viewed. Aperture is the important aspect, not power. If there is not enough light to see the object, it does not matter how many times it is magnified!

There are pros and cons for every type of telescope. You must weigh these aspects to choose the right telescope for your needs. Here are the different types of telescopes with their pros, cons and some price estimates.

Refractors:

These are the scopes most often seen sold in department stores. Just because they are widely available does not mean they are the best or the worst. Refractors are known for the quality of images and are good for light polluted areas. These types of scopes usually do not require much maintenance, so they are good for people that are not technically or mechanically minded. Telescopes with small apertures are easy to transport and assemble. However, these scopes are the most expensive per inch of aperture. A 60mm or 90mm is a good beginner telescope and you can plan to spend anywhere from $100 to $350 for a good scope in these sizes. 

Reflectors:

These are the most economical of all telescopes and even the larger sizes, up to 6 inches, can be transported easily. They are astronomical telescopes and are usually not well suited for land viewing because the image is either upside-down or sideways. However, with additional equipment this can be corrected. Reflectors do an excellent job of deep space viewing, even the more faint objects. However, the mirrors used in reflectors require maintenance more than other scopes. Collimation is needed to realign the mirrors, but this is something owners can do if capable, or it can be taken in for repairs. For a medium sized telescope, 6 inches or so, you could expect to spend $200 to $500.

Schmidt-Cassegrain:

This is the newest kind of telescope and it combines the pros of the other types of scopes into one. Cassegrains are small and extremely portable, they can be used for many different types of viewing, such as deep space, astrophotography and planetary viewing. Many come with a built in motor for tracking objects For this convenience, you will pay. Most are usually priced over $1,000, even for the smaller sizes. The magnification of a scope can be determined by the following equation: telescope focal length divided by eyepiece focal length The focal lengths should be printed on every scope and every eyepiece, so you can easily do the math at the store to find out the magnification. For good images, the power should not exceed 50 or 60 times the aperture in millimeters. Therefore, a 60mm telescope should not exceed 120x. A telescope manufacturer bragging about 500x will give you distorted and blurry images!

For larger telescopes, about 300x is the maximum you would want to go. When you go to buy a telescope, ask questions! If the sales person cannot answer questions about their product, go elsewhere! If you have more questions, feel free to call us at the Planetarium.

239-275-3435 or  planets@calusanature.com