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MAS Frequently Asked Questions


MAS Frequently Asked Questions

Frequently Asked Questions about astronomy (see also MAS Beginners page)

This page answers many commonly asked questions about astronomy. If you have a question on a subject any not covered here, please help support this page by using our on-line enquiry form (requires Java Script to be enabled).

Much of the material here has been taken from topics presented at out monthly meetings. If any member has subject they would like to present for 15-20 miniutes as a 'second half' topic, please contact the Meetings Secretary (to contribute directly to this page, please contact the Webmaster

(+) 0001 How do I find a local Astronomical Society ?

(+) 0002 How is Star brightness measured ?

(+) 0003 What are the Constellations ?

(+) 0004 What is the shape of the Earth ?

(+) 0005 What equipment do I need to start astronomy ?

(+) 0007 What telescope should I buy ?

(+) 0008 How much Magnification can I get ?

(+) 0013 What are Equatorial and Alt Az mounts ?

(+) 0100 How do I use my first telescope ?

(-) 0109 What is a finder ?

The traditional "finder" is a small additional telescope bolted to the main telescope and used like a gun sight' to 'aim' (position) the main telescope = you will be surprised how hard it is to identify a random patch of sky full of stars in the main telescope eyepiece at even low magnifications. The better the finder, the easier it is to find things in the main telescope. The finder and telescope must be aligned with each other for proper use (the finder typically has 2 screws and a spring mounted 3rd axis point that allows simple alignment of the finder with the main 'scope). Some modern telescopes are fitted with 'red dot' (laser) finder. These work by projecting a small red spot onto a transparent screen - the advantage is that you can see the 'dot' from quite a wide angle, so you don't need to get right behind and put your eye right up to the glass (as you do with a traditional finder). Advice: The quality of the finder is important. A finder with 30mm lens is a minimum requirement. Some telescopes are sold with very small finders - these are better replaced with a 'red dot' finder (which can be found on eBay for less than £20). If buying new, see if you can convince the vendor to replace a tiny traditional finder with the 'red dot' type at a competitive cost
This note last modified: 11th Jun 2019 10:58.


(+) 0110 What is an eyepiece ?

(+) 0111 What is a Barlow ?

(+) 0112 What is a focal reducer ?

(+) 0114 What are Nebular filters ?

(+) 0116 How do I use Setting Circles ?

(+) 0120 What is collimation ?

(+) 0125 How can I safely observe the Sun ?

(+) 1030 How can I take photos of the stars ?

(+) 1033 How to take photos of the Aurora ? - (Northern Lights)

(+) 1035 How to calculate FOV for prime focus ?

(+) 1036 How do I calculate FOV for Eyepiece projection ?

(+) 1037 How do I use a Raspberry Pi camera for astrophotography ?

(+) 1038 What is Star trailing ?

(+) 1039 How can I take photos of Meteors ?

(+) 2100 What is Universal Time (UTC) ?

(+) 2114 What are AUs Parsecs and Light Years ?

(+) 2115 What is Bodes Law ?

(+) 3010 When was Neptune discovered ?

(+) 4000 How do I update Stellarium with new Comet data ?

(+) 5000 How To build the MAS (Raspberry Pi) photoframe ?