Beginners’ Guide to Telescopes

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Differences:  What to Consider

IMAGE QUALITY

The brightness & contrast of the image you see is determined in large measure by:

the APERTURE SIZE (diameter) of the main mirror or lens, the bigger, the better for image quality.

the EYEPIECE in use — Look at the number and quality of eyepieces supplied with the scope. 

a FIRM MOUNT with the minimum of vibration and shaking.  Shorter telescope tubes may be less prone to vibration which will cause the image to jump about annoyingly for a while after you touch the scope to move it or re-focus

the QUALITY OF THE OPTICS.  Higher quality lenses, mirrors, and eyepieces will deliver better images, at a price.

OBSERVING CONDITIONS In towns and cities there’ll be significant light pollution and you shouldn’t expect to see faint ‘deep sky’ objects. 

Your eye-sight will also, of course, affect what you can see.

CLICK HERE TO READ MORE ABOUT IMAGE QUALITY

YOUR BUDGET & VALUE FOR MONEY

You can pay a large amount of money indeed for a top quality system.   In general you’ll pay more for bigger aperture size and quality of optics and mount.  Equally you can get a serviceable starter system for around £100-150.

Consider the COST OF LEARNING.  You may want to pay less for your first system and upgrade later when you’ve learned more about observing techniques, equipment, and your own preferences.

 

PORTABILITY

If you live in a town or city you may well want to take your scope out into the countryside away from light pollution.  Consider:

the WEIGHT of the scope and mounting.  Although ‘bigger is better’ for image quality, it will bring more weight.  Some kinds of telescope and mounting are very heavy.

its ROBUSTNESS.  Will it be disturbed by the odd knock?  In general, refractors are more robust.

Simplicity of SET-UP.   You’ll need to set up and align the scope and mounting in the dark.  This can be tricky and will need practice in daylight. An alt-az mount is the easiest to set up.  GPS / auto-align systems align themselves automatically, at a price.

EASE OF USE & MAINTENANCE

SET-UP.  Equatorials need to be set-up pointing at the celestial pole, but rough alignment will do for most beginner’s observing situations.  GO-TOs need more precise polar alignment or they won’t go to anything!  GPS/ Auto-aligns set up automatically at a price.

MOUNTS.  Altazimuth mounts are easier and more intuitive to use but don’t track objects as well as equatorials.   Dobsonians are a kind of alt-az mount and offer more aperture for the money.  A motor drive can make a big difference.  GO-TOs find & track automatically.

FINDER.  The finder scope or star pointer is a vital part of the system.  Look for the quality and position of the finder.

EYEPIECE POSITION.  Small refractors and catadioptrics are more intuitive to use for a beginner because of their eyepiece position.  The eyepiece on a Newtonian reflector with equatorial mount, can get into some difficult positions!

MAINTENANCE.  A reflector needs periodical re-alignment called ‘collimation’.  Can be tricky for a beginner. Also eventually the primary mirror in a reflector will need re-coating (around £100).

What do I need to consider when choosing a telescope?  What are the differences between types?