$refractor telescope$

$refractor telescope$

Larger achromats with objective diameters of 100 mm, 127 mm, and even 152 mm are back in style. You can get an 80 mm or 90 mm refractor and a reasonably solid mount for $300-$400. If you’re mostly interested in the Moon and planets, then an achromatic refractor may be the right scope for you.

$refractor telescope$

But refractors are light, simple to use, mechanically robust, and show sharp images of brighter celestial objects. While generally low maintenance, refractors are expensive compared to their aperture and light-gathering capacity. Still, even achromatic refractors, especially those with a focal ratio of f/8 or less, tend to show false color, especially on brighter objects. This is especially true for refractors with achromatic lenses and a focal ratio of f/10 or longer. Today, all refractors have this type of “achromatic” objective.īecause they have clear apertures with no obstruction, refractors produce the highest contrast of any telescope which makes them superb for visual observation of fine detail on the Moon and planets. In the mid-1750s, a lawyer named Chester Moore invented a refractor with two objective lenses, each of which was made from a different kind of glass to partially correct for chromatic aberration. This caused the images of stars and planets to have colored “halos” and greatly reduced the sharpness of images. They focused red, green, and blue light rays to different focal points, a problem called “chromatic aberration”. Single lens refractors had another problem. A replica of one of Galileo’s first refracting telescope, on display at the Griffiths Observatory in Los Angeles (credit: Michael Dunn). To reduce this distortion, early refractors needed large focal ratios, which meant even telescopes with a small objective lens were enormously long… ten to twenty feet or more. These simple early lenses caused much image distortion near the edge of the field of view. Early refractors like Galileo’s had a single glass objective lens ground to a spherical curvature. The great Italian scientist Galileo also learned to make simple refractors, and he was the first to turn such a telescope to the night sky in 1609.

$refractor telescope$

The First Telescopesĭeveloped by Dutch eyeglass makers in the late 16th century, refractors were the first telescopes. This short article goes through the pros and cons of refractors for astronomy and helps you decide if such a telescope is right for you. They offer amazingly crisp views of the Moon and planets and double stars. With a large glass objective lens at the top of the tube and an eyepiece down at the bottom, refractors are the most robust and conceptually simplest type of telescope. When the members of the great unwashed masses think of an astronomical telescope, they usually think of a refractor. A top-quality refractor telescope (credit: Televue)

$refractor telescope$

Refractor telescope