Many people who decide to purchase a telescope to penetrate the mysteries of the universe. But often feel disappointed to see that the instrument does not serve to those who wait.
First of all there is to know the possibilities of a commercial telescope and above all must learn the mechanics and "geography" of heaven. As before getting permission to drive a vehicle must dominate a little traffic rules for space transit routes should take some classes "astroschool." Only in this way our adventure will not end in total disaster.
To choose well you should know that the telescope has some key parameters:
The diameter or aperture is the size of the target. Indicates the true potential of the telescope. The wider, the greater the amount of light that captures and therefore allows you to see fainter objects and far. In the characteristics shown as $D = X mm$., Where $X$ is the number in millimeters.
For a buyer nobel can indicate that the acceptable minimum aperture is $60 mm$ in a refractor and $100$ or $114 mm$. a reflector.
If the budget allows and the hobby is promising is advisable to choose 80 or 90 mm. and 150 mm in refractor. in the reflector.
Larger sizes are recommended only for observers with some experience. Therefore, the system sold aperture $Schmidt-Cassegrain$ is the $8-inch (203 mm.)$, As fans normally acquire advanced knowledge.
It is not uncommon to see small telescopes that are typically sold in non-specialized stores with great enthusiasm to announce that we will $500x$ or $750x$ increases. The reality is that never achieve much in a small telescope magnification: the images will turn dark and blurred, as there is a proper limit for each telescope, which is well below these vast amounts of magnification.
The amount of increases that we can give our telescope is directly dependent on the diameter of the lens. That is, the size of the input light having. In the case of a reflecting telescope (composed of special mirrors) is the primary mirror diameter of the involved. In the case of a refractor telescope (compound lens) the diameter of the lens. By nature, the lens diameter determines the amount of useful magnification that will give us a telescope. To make a simple quick calculation, the maximum amount is usually estimated as twice the diameter in millimeters, if we see a refractor telescope with a main lens diameter $70 mm$, we estimate that the maximum increase that we will be about $140x$, comfortable and enough to see the major planets and close-ups of the moon.
In short, more increases is not synonymous with better. Remember that what we want are clear images. And keep in mind that commercial telescopes exaggerate this issue as part of the sales strategy. Just do not pay attention.