What’s the difference between Refractor and Reflector?
Q. What’s the difference between Refractor and Reflector?
A. Thank you to Celestron for the following information;
- Refractors use an objective lens to refract or bend light to a point
- Offers highest contrast images of any telescope design
- Perfect for astronomical or terrestrial viewing
Disadvantages – Very expensive to produce in apertures over 100 mm, can suffer from chromatic aberration - a violet or yellowish halo around a bright target.
There are two basic types of refracting telescopes
- Achromatic – Uses a two element objective (a doublet) that brings red and blue light to focus as closely as possible.
- Apochromatic - Uses a three element objective (a triplet) that brings red, blue, and violet to focus as closely as possible. The third element is usually made of a special fluorite or ED glass.
Newtonian Reflecting Telescopes
- Reflectors use a spherical or parabolic objective mirror to focus light
- Light enters the tube, striking the primary mirror, reflects back up the tube to a flat secondary mirror and exits out of the side of the tube into the eyepiece
- Mirrors must be collimated (aligned perfectly) to give the sharpest image
- Contrast is lower due to central obstruction caused by the secondary mirror
- Perfect for astronomical viewing, but not recommended for terrestrial as this design yields a “rotated” image