Refractors (also known as dioptrics) are what the average person identifies with the word "telescope", a long, thin tube where light passes in a straight line from the front objective lens directly to the eyepiece at the opposite end of the tube.

Advantages

• Easy to use and reliable due to the simplicity of design.
• Little or no maintenance.
• Excellent for lunar, planetary and binary star observing especially in larger apertures.
• Good for distant terrestrial viewing.
• High contrast images with no secondary mirror or diagonal obstruction.
• Colour correction is good in achromatic designs and excellent in apochromatic, fluorite, and ED designs.
• Sealed optical tube reduces image degrading air currents and protects optics.
• Objective lens is permanently mounted and aligned.

Disadvantages

• More expensive per inch of aperture than Newtonians or Catadioptrics.
• Heavier, longer and bulkier than equivalent aperture Newtonians and catadioptrics.
• The cost and bulk factors limit the practical useful maximum size objective to small apertures
• Less suited for viewing small and faint deep sky objects such as distant galaxies and nebulae because of practical aperture limitations.
• Focal ratios are usually long (f/11 or slower) making photography of deep sky objects more difficult.
• Some colour aberration in achromatic designs (doublet).
• Poor reputation due to low quality imported toy telescopes; a reputation unjustified when dealing with a quality refractor from a reputable manufacturer.