TELESCOPES

Strengths

Weaknesses

Refractors

Image generally brighter with better contrast

Image will show some degree of false colour fringes (chromatic aberration) except in more expensive types (APOs).

Watch out for restricting ring baffles called ‘stops’ which reduce the effective aperture to disguise aberration in some cheap refractors

More robust — optics less sensitive to knocks

Typical starter refractors may have longer tubes more prone to vibration and shaking causing the image to jump and blur.

Lower maintenance — no periodic re-alignment or re-coating required

More expensive than reflectors for same size aperture

Can be more intuitive to use for a beginner

Closed tube may take longer to cool to outside ambient temperature

Eye-piece, with star diagonal, will mostly be in an easily-accessible position

Finder may be in a less accessible position

Smaller apertures can be inexpensive and easy to transport and set up

Larger apertures can be very expensive and weigh a lot

Reflectors

No false colour fringes (chromatic aberration)

May suffer ‘coma’ distortion at the edge of the field of view

(Newtonians and Dobsonians)

More aperture for your money

Some loss of contrast caused by obstruction from secondary mirror

Eye-piece (at top of tube) may be more accessible

On an equatorial mount, the eye-piece, finder, and controls can get into a difficult position as you track across the sky during a session

Finder may be more accessible than on a refractor

Generally less robust — may be more prone to knocks

Newtonians with longer tubes may be prone to vibration and shaking

Larger sizes are very bulky

Larger apertures may take longer to cool down to outside ambient temperature

More maintenance needed over time — periodic collimation and eventually, re-coating of the primary mirror

Maksutovs and SCTs (Catadioptrics)

Wider field of view with generally good brightness and contrast

Less contrast than a refractor

Short tube for given aperture — less prone to vibration and very portable

More expensive per unit aperture

Can be quite intuitive to use for a beginner (short tube, eye-piece at bottom)

Negligible colour fringes or coma distortion