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Telescopes, I dont sell them! a quick guide, Refractors

by: torana68( 360Feedback score is 100 to 499) Top 100 Reviewer
5 out of 5 people found this guide helpful.
Guide viewed: 169 times Tags: refractor | telescope


Rule number one - you get what you pay for!

Rule number 2 - If you dont know find out first!

 is this going to be your first telescope? then your at a huge disadvantage and sellers are going to take advantage of that!

You like astronomy, or at least the thought of it, pop into a newsagent and get a copy of one of the astranomical magazines for your country (Australian Sky and Telescope for example). Look at the prices, read the articles, NOW THINK! ..... is that 99c start Telescope really the equal of the $2000 one. NO ITS NOT, its probably junk or a childs toy.

The size of the apparture and the quality of the optics is the important bit

This is a bit of basic advice not intended to be overly technical

Refractors are generally the long thin telescopes, they have been around since about 1600, you look "through" them ,Reflectors , the fat ones, have mirrors that "reflect" the light.

Beware adds for 1000x 'scopes, this is rubbish, the best 'scopes for home use rarely go past 200x magnification, this is with the best optics on the best nights. 1000x? forget it. The larger the objective (lense) and the more light that is gathered, the more magnification that may be used.

there are two main types

The Achromatic refracting lens was invented in 1733 . The design overcame the need for very long focal lengths in refracting telescopes by using an objective made of two pieces of glass.

Apochromatic refractors have lens's (3) built with special, extra-low dispersion materials, these are expensive, new in the $$$thousands area

GOTO

     A goto Telescope has electronics to guide it, this can be expensive, if you get one make sure its from a known maker and you can get software updates .You are probably better spending the extra on good quality optics, its the optics that let you see things, the electronics just point the telescope.Use your in built computer (the one between your ears) to find things in the sky.

Focal length

     Refractors are normally a longer focal length to Newtonians, F15 being common where with Newtonians f5/6 is common.

FAKE ANTIQUES AND DOGY DEALINGS

yep unfortunately a lot of the brass/antique refractors are actually "made in India" copies beware the seller who claims "I bought this at an estate sale and know nothing about it." . Find out how to tell a fake, try googling antiquetelescopes.org they seem to have a good idea.

left is a fake "Henry Barrow"on the right a fake "Ross"  beware!!!!

MOUNTS

The equatorial is the one for these but a wobbly thin/light one wont be a lot of fun, if it looks like a mount for a video camera forget it. You will find it a total pain to locate distant objects with a wobbly mount. This is a slightly complex subject so google "German Equatorial Mount" and see how you go, stay away from cheapie ones you'll hate them. If you have a bad back try a Newtonian on either a Dobsonian or GEM mount. you'll do a lot more bending with a Refractor (Newtonians are also lighter in general when you get up to real hobbiest sizes, smaller ones could be a lighter choice if you need to consider small size and weight)

                                                             

this is a high quality GEM                                                   This is a cheapie maybe A$200

it would cost you A$4,000 ish (yep just the mount!)             Quality difference? just a lot!

       So... before you decide , read magazines or books, search the net, maybe even join a club, the answers are out there. At the very least get some idea of what you are likely to see through a particular scope. try "backyard voyager" on the net and look at his "bascis" pages.

   A couple of parting thoughts, Google "buying your first telescope in Australia" its a good read. Try on line groups like "Cloudy Nights" and "Ice in Space" for info or try "Australia Astronomy buy and sell"

"If you want Ferrari preformance dont buy a Hyundai - you'll be dissapointed!"

if this was helpfull or even just interesting please tick the little box below, ta, Roger

send suggestions for updating this guide, im open to your input.


Guide ID: 10000000012437545Guide created: 18/06/09 (updated 23/10/09)

 
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