Definitions

1. Refractors are less affected by atmospheric instabilities, making them perfect for observing the moon and planets.
2. Refractors are the type of telescope that most of us are familiar with.
3. Refractors are criticized for their relatively high-degree of residual chromatic and spherical aberration. (Web site)
4. Refractors are relatively expensive, if you consider the cost per unit of aperture.
5. Refractors are easy to use, require no maintenance and can be affordable even when mounted on an equatorial mount. (Web site)

Extra-Low Dispersion

1. Since that time, many new glass types for refractors have become available, such as ED (extra-low dispersion) glass types.

Reflecting Telescopes

1. When techniques for depositing metal films on glass surfaces were developed, reflecting telescopes became comparable in precision to refractors.

Collimate

1. Refractors generally haved fixed optics, so you don't have to collimate them. (Web site)

First Telescopes

1. The first telescopes built were refractors. (Web site)

Land Refractors

1. Using telescopes for land viewing will point you in the direction of the land refractors.

First Refractors

1. Balancing Eyepieces Cleaning The first refractors were known for their chromatic aberration. (Web site)

Giant Refractors

1. They stand tall and proud on their mountings like the giant refractors at the great observatories.

Equivalent Aperture Refractors

1. Large apertures at reasonable prices and less expensive than equivalent aperture refractors.

Useful

1. Now "reflectors" are the norm for large telescopes, though refractors remain useful for small instruments.

Common

1. Dew caps are common on refractors, but often are useful on Schmidt-Cassegrains and Maksutovs. (Web site)
2. As is very common of many commercial refractors today.

Look

1. Most telescopes (but especially refractors) can be hard to look through when pointing at things high overhead.

Large

1. Refractors have fairly good resolution, but it is very difficult to make the lenses that go into them very large.

Instruments

1. Prices for refractors have fallen dramatically in recent years as Chinese products overwhelmed home markets for these instruments.
2. Among the instruments that he had were achromatic refractors, astronomical clocks with compound pendulum, and an excellent transit instrument.

Design

1. This is the design used in modern refractors.

Contrast

1. They offer the clarity and contrast of refractors with the low aberration of reflectors.

Familiar

1. If you are familiar with a prism or a rainbow you can understand why reflectors are superior to refractors.

Market

1. Nearly all birding scopes on the market today are refractors. (Web site)
2. Very good refractors, on the other hand, are also on the market if you are willing to hunt them out and pay for them. (Web site)

Advantage

1. Refractors have the advantage of rendering sharp high-contrast images, large image scales (due to higher focal ratios) and excellent resolution. (Web site)

Diagonal

1. Slight light loss due to secondary (diagonal) obstruction when compared with refractors.
2. Most short-tube refractors are designed to be used in conjunction with a diagonal. (Web site)

Images

1. Like refractors, their closed tubes keep optics clean and prevent air currents in the tube, which sometimes disturb images in reflectors. (Web site)
2. This disparity is most apparent when viewing low-contrast planetary detail — the images in a good refractors often have a touch more snap to them. (Web site)
3. One of the downfalls of inexpensive refractors is that for astronomical viewing, they have the tendency to add false color to images.

Observers

1. Many observers swear by their refractors and believe them to be unrivaled for sharp lunar, planetary and binary star observing.

Rugged

1. Refractors of all kinds are rugged, require little or no maintenance, and have sealed tubes that keep out dust and reduce image-degrading air currents. (Web site)

Objectives

1. Apochromatic refractors are available with objectives of up to 553mm in diameter, but most are between 80 and 152mm. (Web site)

Small Telescopes

1. The small telescopes sold in department stores are refractors, as well as, those used for rifle scopes. (Web site)

Planets

1. If it is just the moon and the planets you want to look at then you should now that refractors are better than reflectors for this. (Web site)

Celestial Objects

1. And, if you're interested in viewing both land and celestial objects, refractors are equipped for both uses.

Effect

1. In contrast, refractors and mirror-lens designs are devoid of this effect as no vanes or suspension rods are employed. (Web site)

Spherical Aberration

1. Refractors have been criticized for their relatively high-degree of residual chromatic and spherical aberration. (Web site)

Focal Lengths

1. May have a narrower field of view (Maksutov's) when compared to similar aperture Newtonians or Refractors due to longer focal lengths.

Short Focal

1. More compact than most refractors (short focal length).

Kind

1. Commonly known as refractors, telescopes of this kind are used to examine the visible-light region of the electromagnetic spectrum.

Dioptric

1. Telescopes that create their image with an objective that is a convex lens (refractors) are said to be "dioptric" telescopes. (Web site)

Advantages

1. Reflecting telescopes have a number of other advantages over refractors.

Refracting Telescopes

1. Refracting telescopes, or refractors, are the type of telescope most people think of when they picture an astronomy telescope in their minds.

German Equatorial Mount

1. German Equatorial Mount The first equatorial mount devised and still the most common for small to moderate sized reflectors and refractors. (Web site)
2. German Equatorial Mount A mount used primarily with refractors and reflectors.

Lenses

1. So long as lenses are made of glass, the 40-inch (1-meter) at Yerkes represents the practical limit in size of refractors. (Web site)
2. Except for the way in which tubes are manufactured and lenses are ground today, the designs and principles of refractors have changed very little. (Web site)
3. In the achromatic refractors the lenses are specially designed to reduce this effect; most refractors available to buy are achromatic refractors. (Web site)

Catadioptric Telescopes

1. Finally, there are catadioptric telescopes, which combine elements of refractors and reflectors in their design. (Web site)
2. The focusing mechanisms of Catadioptric telescopes are different than in reflectors and refractors.

Small

1. Perfect for first-time and novice astronomers, small refractors are lightweight, portable and require very little maintenance.
2. These small refractors could give a nice view of the moon or the planets.
3. Back in the early days of amateur astronomy, observers with small refractors tracked down hundreds of these astronomical jewels. (Web site)

Larger

1. Larger refractors, however, become very expensive and are typically bought by avid enthusiasts. (Web site)
2. Reflectors tend to be heavier and larger than refractors.

Apo

1. Used in APO refractors and is very expensive. (Web site)
2. The visual and imaging benefits of apo refractors have helped to make them instruments of choice by many real-time observers and imaging experts alike.
3. We love those premium "apo" refractors as much as the next guy.

Newtonian Reflectors

1. Schmidt-Cassegrains, Newtonian reflectors, and refractors all have good and bad points.
2. The German equatorial mount is most commonly encountered form for refractors and Newtonian reflectors.

Disadvantages

1. The least expensive types of telescopes such as refractors and Newtonian reflectors, both have many advantages and disadvantages.

Vixen

1. Vixen is particularly noted for refractors with fluorite doublets, and for Lanthanum LV eyepieces. (Web site)
2. Apochromatic refractors from Vixen have extra-low dispersion (ED) lenses that depress residual aberration to achieve a high level of performance.

Catadioptrics

1. Refractors can transmit 90% or more of the light they collect, compared with the 77% to 80% transmission of reflectors and 64% to 75% of catadioptrics.
2. More fragile than Refractors or Catadioptrics and thus require more maintenance (such as collimation). (Web site)
3. Other designs such as refractors and catadioptrics (specifically Maksutov cassegrains) have fixed collimation. (Web site)

Cost

1. Refractors gather more light than reflectors of the same size, but because of their cost mainly, they are not made to the same sizes as reflectors. (Web site)

Expensive

1. In general, refractors are much more expensive to build and buy than are reflectors. (Web site)
2. Refractors and SCT's are typically more portable, but may be more complex and more expensive. (Web site)
3. Apochromatic refractors are much more expensive than achromatic refractors.

Categories

1. Reflectors
2. Information > Science > Astronomy > Telescopes
3. Science > Physics > Optics > Chromatic Aberration
4. Objective Lens
5. Basic Types

Related Keywords

* Aperture * Apertures * Basic Types * Chromatic Aberration * Eyepiece * Eyepieces * Inch * Light * Objective Lens * Objective Lenses * Reflector * Reflectors * Telescope * Telescopes * Types

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