To find out which model your Sky-Watcher telescope is, you will need to know the Diameter and Focal Length of your telescope, and the model of your mount. Near the focus tube you should see a sticker with technical information of the telescope. For example, if you see “D=130mm F=900mm", the diameter of your telescope is 130mm and the focal length is 900mm. You should be able to find the name of your mount on the assembly manual that comes with your telescope. The instruction manual will be titled “Reflector/EQ2 MOUNT", if your mount is EQ2 mount. In this particular case, the model number of the telescope is BK1309EQ2.

A simple mount that allows movement in altitude vertical plane (up and down) and in horizontal plane (azimuth/ side to side).

A barlow lens has a negative focal length which increases the effective focal length (E.F.L) of the objective lens or mirror of the telescope. It is always placed between the objective and the eyepiece and results in increased magnification and decreased field of view.

A system using both lens and mirror components to produce an image. These telescopes to be more compact than other designs.

A tube extending forward from the front lens of a telescope. It prevents dew from forming on the lens as it cools down, and acts as a sunshade to reduce reflections during the day.

A mirror or prism system which changes the angle and orientation of the light rays coming from the telescope to the eyepiece.

A telescope mount with an axis parallel to the axis of the earth. This provides easy tracking of sky objects and for photography when combined with a clock drive.

It is also called an Ocular. This is a small tube that contains the lenses needed to bring a telescope's focus to a final image in the eye. Telescopes usually come with at least two eyepieces: one for low power and a second for a higher power view.

This is usually a disk of coloured glass or film that sits in front of the telescope eyepiece or objective. It rejects band of wavelength while transmit others. (It is important to remember that a Solar filter must always be placed in front of the objective.)

A low power telescope attached parallel to the main instrument which provides easy object locating and telescope aiming by keeping larger field of view.

A device which brings the light rays in a telescope to a precise focus. Common designs include geared (rack-and-pinion), gearless (Crayford-style) and helical.

An eyepiece with an Apparent field of more than 50 degrees.

An optical system which provides a variable focal length. Sky-watcher have Zoom lenses 7-21 and 8-24.