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the very basics:
Most telescopes have two numbers divided by a / in their name, this describes their aperature and focal length.
My telescope is a skywatcher heritage 130/650, the first being the aperature, the second being the focal length, all in millimeters:
>aperature
how wide the opening of your telescope is. This affects how much light it can gather, the bigger you can afford (and manage in size) the better
>focal length
the distance light travels from the aperature to the eyepiece.
The relationship between aperature and focal length determines your magnification (in combination with an eye piece)
>Eye pieces
also have a number on them showing their focal length, also in mm. My telescope came with two different ones, a 25mm eye piece and a 10 mm.
To calculate the magnification, you simply divide the focal length of the telescope by the eye piece. For my telescope, thats 650/10= 65x magnification, or 650/25= 26x magnification.
>Barlow lenses
Additionally magnify. You place them inbetween the eye piece and the telescope. A 3x barlow lens then gives me 195x magnification with my telescope and the 10mm eye piece (65 multiplied by 3)
