TELESCOPES
2
Reflecting Telescopes
- excellent light gathering power - the bigger the better
- cheapest per centimetre of aperture
- wider field of view than refractors
- Some maintenance required (re-coat the mirror faces every 8-10 years, re-align mirrors
if necessary)
- optics are not enclosed, but can be cleaned ocassionally
- Lower resolution due to secondary mirror obstruction, generally suited better for faint objects
The larger a telescopes aperture (size) the more light gathering power and better resolution it has.
There are billions of other objects in the sky, but they cannot be seen until a telescope is used. Our eyes have a maximum aperture of 8mm and a magnification of 1x. To an extent increased aperture size allows more magnification. The brighter an object, the more the light can be spread out through magnification. When an object is magnified twice (2x), the light is only a quarter as bright. With increased magnification, atmosphere heat waves, air pollution and dust in the air etc., it is hard to get good focus of an object. This means the highest magnifications can only be used on the clearest, stillest nights. Generally a maximum of 300x magnification can be used on any night. It is important to stress that every night is different. Sometimes it won't be possible to use 300x, but on other nights, the viewing may be exceptional and magnifications will be able to far exceed 300x.
The minimum aperture for astronomical use is 60mm for a refractor and 80mm for a reflector. Ametuer telescopes are available up to 1 meter in diameter as a reflector.
It's better to start with a small telescope and see the many objects available for a small price tag. If you wish to see more objects or in greater detail, then it's time to move up!
for schools
Maksutovs
Australian
Residents Please Call (08) 8381 3188
International Residents Please Call 61+ 8 8381 3188
Australian Fax Orders (08) 8381 3588
International Fax Orders 61+ 8 8381 3588
