A Brief Explanation Of Telescopes

60
Spring, Summer, and Fall are all great times for using a telescope.  I don't particularly like the winter as it's just too cold for me.  I've seen some deals for telescopes on DP and even a question in Ask & Share section  inquiring about them.  This Page provides some of the basics to get you started if you currently know little or nothing about the subject.

Telescope come in two broad types with sub-types within.  The two major types are refractors and reflectors.


REFRACTORS: Refractors use glass lenses to concentrate light.  Light enters the telescope through an objective lens.  It is the size of that lens that you will see advertised for a telescope of that type.  A 3" refractor will have a 3" glass lens.  After the light passes through the objective lens it is focused through several (the amount varies) other lens and the final image is routed to the eye piece which actually magnifies the image.  The job of the objective lens is to gather light and concentrate the image.  Refractors don't have the central obstruction that is part of the construction of a reflector. Refractors can be very inexpensive and a great way to start out with astronomy.




REFLECTORS:  Reflecting telescopes concentrate light through the use of mirrors.   In the simplest of these telescopes, the Newtonian, two mirrors are used.  The first mirror is called the primary mirror and again, that is the size that you will see in an ad for a reflecting telescope.  A 5" reflector has a 5" primary mirror.  The primary mirror focuses the light into a cone and a second mirror reflects the image to an eye piece.  Reflectors often cost a bit more than refractors but do a better job of keeping all colors in focus simultaneously; something with which refractors can struggle.





Tripods & Mounts: The mounts for telescopes can be as simply as up/down & left/right which are called Altazimuth mounts (not good for tracking).  Other mounts will have a more complicated system that allows for movement in three axis so that once an object is in focus it is a simple matter to track it.  These are called equatorial mounts (good for tracking).  You can even buy motorized mounts with a computer controller that will find an object and automatically track it.  It really depends on how much money you want to spend and do you want to be able to track an object for a while without constantly adjusting the mount.  If you are going in for astrophotograhy you will need a mount that can track very accurately and smoothly so that your photo is not blurred or otherwise out of focus.



I am not an advanced hobbyist by any means but I have dabbled in astronomy since I was a teenager and took a course in astronomy as an undergraduate at the University of Maryland.  There are probably folks within the DP community that know a great deal about the subject (my apologizes to them for over-simplifying these concepts) and I hope they chime in with some comments.

If you are just starting out I would recommend that you spend at least $150 or so (which should get you a $200+ retail value scope) and if you can stretch to $300 you can actually get a very nice telescope that should provide a lot of enjoyment.  I have a close friend who is deeply into the hobby and has spent about $150,000 on his setup.  He paid $6,000 just for the mount.  You could spend more than that but you don't have to by any means.  As an example, I own this little guy that I got on sale for $35 last Christmas and it is currently on sale for about $55 at Amazon here (retail is about $80)/  You can carry it under your arm and it is great for looking at visible objects in the sky such as the moon and the brighter planets and constellations.  You can even use this to get a glimpse at satellites.


Celestron FirstScope Telescope:It's a diminutive little scope but very portable and for $55 you can't go wrong.  

Thanks for reading.  I hope you found this useful, and please leave questions in the comments area.  I or someone else who knows a bit or a lot about the topic will be happy to provide answers.  For additional reading you will find that Astronomy.com (Astronomy Magazine's website) has a great deal of free content.


erick99 posted May 03, 2012
1037 views
Facebook Share
Twitter
12 Comments
dealwagger
It is so amazing that such relatively simple parts can be put together to see so far into the distance! I wonder how the first person who did this even thought of it!
dealwagger (rep: 10.2k) posted May 03, 2012
30
MaryRolle
That little firstscope looks like a great gift idea for my granddaughter! Great article, thanks!
MaryRolle (rep: 23) posted May 03, 2012
20
erick99
From an astronomy site, "A man named Hans Lipperhey invented the telescope. He was born in Wesel, Germany and made his home in Middleburg, part of the Zeeland province in the Netherlands. He was married there in 1594, and became a citizen in 1602. He was a spectacle-maker by trade."
erick99 (rep: 17.4k) posted May 03, 2012
10
erick99
I had read, some long time ago, that he more or less accidentally discovered that two lens, held some distance apart, would magnify a distant object. Others such as Galileo and Newton did a great deal more work perfecting the idea.
erick99 (rep: 17.4k) posted May 03, 2012
20
erick99
I was digging around for an idea for an article so my thanks to Florida2Texas for inspiring this one :). I will be taking the little scope out tomorrow night to view the full "super perigee" moon and introducing my girlfriend to astronomy at the same time.
erick99 (rep: 17.4k) posted May 03, 2012
10
Florida2Texas
Makes me feel like a tutorial made just to meet my needs. I would like to thank you professor Eric for such great information! :)
Florida2Texas (rep: 10.6k) posted May 03, 2012
20
erick99
Thank you!! While I shamelessly stole all of the graphics & photos, I can promise you that the text is all mine lol
erick99 (rep: 17.4k) posted May 03, 2012
10
Zoey2011
My God, does your friend have a wife??
Zoey2011 (rep: 30) posted May 03, 2012
20
erick99
He does have a wife but no kids and he and his brother own an insurance agency. I really envy his disposable income :)
erick99 (rep: 17.4k) posted May 03, 2012
10
rockinnrolla
Very interesting! Thanks erick99!
rockinnrolla (rep: 159k) posted May 04, 2012
10
ArtemisDeals
Dang! Way to go erick99 :) I like your articles :)
ArtemisDeals (rep: 7.16k) posted May 04, 2012
00
erick99
Thank you, ArtemisDeals!
erick99 (rep: 17.4k) posted May 04, 2012
00