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alklb
2003-Dec-08, 12:11 AM
Please tell me what the difference is between the reflector and refractor? I am told one shows things upside down?

aurora
2003-Dec-08, 12:45 AM
Please tell me what the difference is between the reflector and refractor? I am told one shows things upside down?

A reflector uses mirrors. A refractor uses lenses.

Different types of telescopes usually view objects in different orientations (upside down, left-right swap) but for astronomy it really makes no difference. The only time it would make a difference would be if you were going to use the telescope in the daytime to look at birds or whatever. Then you would want a prism that presents the image right side up.

Before buying a telescope, do some research. Look for the book StarWare in your local library, or search online as there are lots of good articles available.

Glom
2003-Dec-08, 12:49 AM
Try Backyard Astronomer's Guide by Dickson and Dyer. That's very good. And, don't buy any telescope that is advertised on the basis of magnification, eg, "Powerful 675X model". It's a sure sign it's trash. All telescopes should be advertised in terms of aperture, eg, 60mm refractor.

alklb
2003-Dec-08, 01:09 AM
Does this mean that we would see things upside down?

Sam5
2003-Dec-08, 01:49 AM
Does this mean that we would see things upside down?
A “reflector” is cheaper, but it sees things upside down. It has the big mirror. It’s usually cheaper and a little brighter, but you can’t use it on earth to look at distant earth objects, because everything will be upside down.

You might be able to add an “erecting prism” to it.

A “refractor” has just lenses, a big glass up front and a little one in the back. It sees things right-side up.

When people want high power and brightness just to look in the sky at night, they usually go with a “reflector” with the mirror because it is cheaper for its size, and they don’t care if the moon and planets are seen upside down. But if you want to look at birds and things on earth too, you need to go with a “refractor”.

Kaptain K
2003-Dec-08, 08:34 AM
Actually, astronomical refrators also give an inverted (upside down) image. If a scope gives an upright image, it has an erecting prism in it.

cyswxman
2003-Dec-08, 01:07 PM
Welcome to the board, alklb!! :) :)

...And for being our 3000th registered user!!

ZaphodBeeblebrox
2003-Dec-08, 03:58 PM
Welcome to the board, alklb!! :) :)

...And for being our 3000th registered user!!

Now, to tell you what you've won ...

SarahMc
2003-Dec-08, 04:05 PM
Please tell me what the difference is between the reflector and refractor? I am told one shows things upside down?

As others have stated, it's not a big deal with astronomy, only for terrestrial viewing. What you should be more concerned with, is whether you'll use the scope. An unused scope (for whatever reason) is worthless.

Refractors use glass lenses, much like a lens on camera. Less expensive refractors called "achromats" have some discoloration on bright objects due to chromatic aberrations. A good "apochromatic" scope will run well into thousands of dollars. Nonetheless, a good achromat can make an excellent telescope for the beginner. Small refractors are nice because they're portable, and typically are very good on planets. They can also double as a terrestrial scope with the proper diagonal or erecting prism.

Reflectors (using mirrors instead of lenses) cover a much wider variety of scopes, from Newtonians to Schmidts, Maksutovs and Dall-Kirkham designs. They're typically larger apertures making them suited well for deep space objects (galaxies, nebulae, clusters, etc). They do well on planets if they're collimated properly. Typically they aren't seen in terrestrial use because of their size, but smaller Maksutovs are sometimes seen being used for that purpose. Even some camera lenses are of the Maksutov design. Their size also limits their portability.

Before you buy a scope, read some of the faq's, including the one here on Bad Astronomy. Buy a beginners book, and locate the constellations and major stars, Use binoculars if you have them, they're quite useful. Join and astronomy club in your area and attend some star parties, where you can look at scopes in use, look through different models, and get an idea of what their owners think of them. Price is always a consideration, but don't be hasty - a good telescope that will fit your needs may be a little expensive. An inexpensive scope could possibly ruin your interest in the subject.

As someone above stated, stay away from the Tasco's and Jason's that advertise the "650X" magnification. Magnification isn't relevant. The amount of light the scope can gather is (aperture) , the quality of the optics (coatings, figuring, materials, alignment, etc), and the stability of the mount are what make a good telescope. Being portable is a big plus, especially if you have to travel to a dark site, or outside the city. If the scope you buy is too large or heavy, or if it has an unstable tripod or mount, or if the optics are so poor you can't see much more than with binoculars, you'll never use the scope and you'll be frustrated quickly. So, take the time to look through other people's scopes, talk with them, and prioritise what your needs will be ahead of time.

So, there's lots of options, and lots of room for mistakes. Take your time in choosing a scope, and inform yourself well before buying. Above all, don't expect to see the wonderful colors that are seen in astrophotographs. Other than the planets, you won't be seeing very much color at all.

This site shows some different types of scopes (http://www.celestron.com/tb-2ref.htm)

Astronomy clubs around the word (http://www.sky-watch.com/links/clubs.html)

Telescope Buyers Faq (http://www.weatherman.com/purchase.htm)