You what?

[popeye85]

Hi there. I'm looking g for some one to help new get to grips about all the terms when it comes to optics. Focal length, ratio,eye pieces etc. I will be getting a skywatcher discovery 150. I understand about aperture but that's about it! Not got a clue about the rest of it or pros and cons of different bits!thanks in advance!

[kendg]

The BAckyard Astronomer's  Guide is and excellent book to get you started.

[D4N]

Focal length - the optical distance between the primary (big mirror or first lens) and the focal plane (where the eyepiece goes).

Focal ratio - the ratio between aperture and focal length. A smaller number means a faster scope ( it collects light faster), fast scopes are less forgiving of optical aberrations and harder to focus but will give a brighter image. It isn't something you need to worry about for visual but it has a profound impact on imaging.

Eye pieces - high number gives low magnification, low numbers give high magnification. Divide telescope focal length by eyepiece focal length to get magnification.

Barlow - used in front of an eyepiece to increase the magnification. Will be labelled 2x 3x etc.

Reducer - the opposite of a Barlow. Will be labelled 0.8, 0.6 etc.

Aperture - bigger aperture give better resolving power, more detail.

Reflector - a telescope that uses mirrors.

Refractor - a telescope that uses lenses.

That nearly scratches the surface of what is a very complicated hobby!

/Dan

Sent from my iPad using Tapatalk

[Floater]

Popeye, you are getting/have been given the best of advice. And that is what this forum is known for. Dan and Ed's responses are testament to this.

But, really, you just have to Google these things and you'll find all the information you need. Part of the fun of this hobby - to my mind - is finding the answers to questions and learning more about how all these things work.

Go on! Have fun ...

[Putaendo Patrick]

Basically you point the big end towards the sky and poke the little end into your eyeball - least that's the way refractors seem to work.

Seriously, a very good introduction to different types of telescope and how they function is A Buyer’s and User’s Guide to Astronomical Telescopes and Binoculars by James Mullaney, second edition 2014.

A very enjoyable and well illustrated history of the evolution of the telescope is Eyes on the Sky, The story of telescopes by Biman Nath. The version I have was published in India in 2009, though, so it may not be easy to find.

If you happen to have a PhD in maths and physics, you may understand The Principles of Astronomical Telescope Design by Jingquan Cheng, 2009. It's not designed for idiots like me though.

All said, you'll soon enough pick up the technical jargon. Good luck!

[Alan64]

I'd strongly suggest this kit instead...

http://www.firstlightoptics.com/reflectors/skywatcher-explorer-150p-az4-mount.html

True, it's not motorised, but the optical tube is of much better quality, and where it really counts in the end.  It has a 2" focusser, and for the use of 2" eyepieces in future.  The other has only a 1.25" focusser.   

[laudropb]

Lots of very good advice given above. I would only add that you should buy from an astronomy dealer rather than the Internet or high street photography shop. You will almost certainly gear better advice and after sales service

[popeye85]

Guide to Backyard Astronomy

http://www.wwnorton.com/college/astronomy/astro21/sandt/backyard.html

Crash Couse on Astronomy – PBS Video Series

https://www.youtube.com/playlist?list=PL8dPuuaLjXtPAJr1ysd5yGIyiSFuh0mIL

EYEPIECE BASICS

https://www.youtube.com/watch?v=DODk3cJam68

http://old.observers.org/beginner/eyepieces.freeman.html

Barlow Basics

https://www.youtube.com/watch?v=ENCbtFpdKJ0

Collimation - How to Collimate a Newtonian scope Collimation cap or laser

This shows an Orion Dosonian but yours will work the same way.

https://www.youtube.com/watch?v=YAVGcGEBmCE

Choosing your magnification

http://www.skyandtelescope.com/astronomy-equipment/choosing-your-telescopes-magnification/

Degrees, Arc minutes and Arc Seconds – a primer

http://oneminuteastronomer.com/860/measuring-sky/

Star hopping 101 – Video play list

https://www.youtube.com/view_play_list?p=36B0AD5D29A76981

Cheers!it's (almost) starting to make sense now! The'telescope basics' series was a good send!