Telescopes are optical instruments used to focus and magnify distant objects. They come in a wide variety of designs but all telescopes use either a lens or a mirror (or combination of the two) to magnify and focus.

Telescopes that utilise a lens for this purpose are called 'Refractor' telescopes, as the light entering the telescope is refracted (focused) to a point by the lens.
Refracting telescopes are used to view a wide variety of astronomical objects including planets and deep sky objects.

Refractor Telescope Design

Two main variations of refractors exist :

• Achromatic (two lens) &
• Apochromatic - (three or more lenses) including many Vixen refractors.

Reflector telescopes utilise curved and flat mirrors that reflect light to a point at the eyepiece. These telescopes are capable of being constructed to a much larger size than refracting telescopes, and as such are used primarily for viewing deep sky & faint objects, although they can be used to view planets.

Reflector Telescope Design

Reflectors are usually mounted in two ways:

• On a German Equatorial mount - that allows automatic tracking or
• On a Dobsonian mount - allowing for manual movement of the telescope.

Catadioptric telescopes combine both mirrors and lenses to magnify an image.
Due to their design, these telescopes are ultra compact and excellent for astrophotgraphy and planetary viewing. Many catadioptric telescopes are available as 'goto' computer driven models. These allow a computer to point the telescope at many thousands of objects in the sky, after an initial alignment.

Schmidt Cassegrain Design	Cassegrain Design

There are three main types of these telescopes.

• Schmidt Cassegrain - the most common type, made by both Celestron and Meade.
• Cassegrain - such as the VC200 series by Vixen.
• Maksutov - such as the ETX90 by Meade.

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Remember : Never look at the Sun with an unfiltered optical device or your naked eye.
It will result in blindness.