Mainly the important features that need understanding before buying a telescope are – Magnification and Aperture.
Magnification or the 'power' is least significant feature to when you are deciding on choosing a telescope. Magnification level of a telescope does not play a better role while looking at the sky. Even though, magnification levels are useful in particular eyepieces and other optical appliances but image quality can severely suffer making it difficult to focus properly. This is a very important point in all buy telescope guide.
A telescope with better light-gathering ability, which depends on the size of the aperture, plays a more significant role in deciding how much you can see. a telescope having larger aperture with reasonable magnification may make the image seem a bit smaller but the image you will see far enhanced quality and in fact see a lot more.
The most significant feature of a telescope is the size of its aperture. An aperture is the diameter of the light-gathering lens or objective lens of the telescope. Typically, an aperture or objective lens size is measurable in millimeters or inches. However, at the same time you need to consider the portability or mobility of your telescope. Well, here you need to understand that bigger the objective lens size heavier the telescope becomes. Therefore, how to choose a telescope needs proper an understanding.