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Eyepiece Telescope

Eyepiece Telescope

How to Use a Telescope - Reflector Telescopes an Introduction

Telescopes are of two main types – reflectors and refractors. The fundamental difference between both types is the kind of glasses used for light collection. Refractors use lenses while reflectors use mirrors. Going back to school physics, it is obvious that light from distant bodies, like celestial objects, comes at us as a parallel beam. Due to this parallel nature of the light rays, Reflector Telescopes use parabolic mirrors.

Such a parabolic mirror focuses each ray of light it receives from the original parallel beam at one single point. Because of this nature of the mirror, a reflector type telescope is far more advantageous in comparison to a refractor. A singularly important point to be noted is that reflectors do not suffer from chromatic aberrations which are a common problem for refractors. This is because, unlike refraction which alters the way in which different wavelengths are refracted, mirrors do not affect the wavelengths at all.

A second advantage is that they are relatively less expensive for the same quality of magnification. Furthermore, since light is reflected, only the reflecting surface needs a perfect finish. In the case of refractors, light has to pass form one side of the lens to the other, as a result of which both refracting surfaces need to be perfectly polished.

Astronomers generally prefer Reflecting Telescopes; however, even these have some disadvantages. The most glaring of these is the difficulty faced in correct alignment of the mirrors. Reflectors are equipped with an open tube, thus the inner optical elements require regular maintenance and cleaning. Without this care, images produced by the telescope end up blurred and indistinct. There are also instances of requiring secondary mirrors to correctly focus light at particular spots. These secondary mirrors can also adversely affect the image quality.

The major disadvantage faced with both refractors and reflectors is that the final image is an inverted image. An easy solution for this fault is the placement of a relay or prism in the passage of light, so that an already inverted image reaches the eyepiece, which again inverts it to produce an Erect Image. This is because the relay or the prism as the case may be, acts as a light ray inverter resulting in a final upright image.

The above paragraphs mention the use of secondary mirrors in reflectors to change the spot of light focus. These secondary mirrors are smaller than the primary mirror. According to historical accounts, Sir Isaac Newton used a mirror that was flat and inclined at 45 degrees as a Secondary Mirror. The purpose of this mirror was to shift the reflected light to an eyepiece at the side of the upper portion of the tube. This arrangement is now known as the Newtonian design and still finds takers.

There is another special design used in reflector type telescopes known as the Cassegrain design. This gives the light from the subject a specific path to reflect it better on the primary mirror. With this design it is possible to position the eyepiece at one’s own convenience. Even Modern Telescopes like the great Hubble Space Telescope make use of this design, and for the advantages discussed above, astronomers lean towards the reflector, and not the refractor.

About the Author

Learn more about home made telescopes as well as professional instructions to build a telescope when you visit http://www.howdotelescopeswork.com, the online portal for free resources on telescopes making

Where to find GSO Super-Wide Telescope Eyepiece?

A lot of you top contributors out there answered my question on buying a 2" eyepiece (q70 or GSO)

After deciding on the GSO, i have searched and searched around the internet only to find reviews of this eyepiece.

I did find a product (on eBay) that was a GSO Super View (68 deg APOV)

Is this the same eyepiece?

Can anyone send me links where to find it? i'd rather order from a company website rather than eBay.

It's actually called SuperView, not SuperWide. Here are two sources, both well-known dealers:

http://www.agenaastro.com/GSO-SV-30-mm-SuperView-Eyepiece-2-inch-p/e-gs-sv30.htm

http://www.optcorp.com/product.aspx?pid=3984&kw=os-s30&st=3

How to Use Telescopes : Telescope Eyepieces

Day or night telescope Photo Mugs This achromatic telescope has a wooden barrel and three brass draw tubes. The other brass fittings include a sliding eyepiece cover, of which the slide is missing. The objective lens cap is also missing. The makers name is engraved on the smallest draw tube as G Dixey London, referring to George Dixey, who is known to have been trading from 1809. The words Day or Night are inscribed on the same dr...

Day or night telescope Photo Mugs This achromatic telescope has a mahogany barrel and a single brass draw tube. The other brass fittings include a sliding eyepiece cover and an objective lens cap. The makers name is faintly engraved on the draw tube as J. Cox a Son, London. The words Night or Day are inscribed below, indicating that the telescope was designed for use in all light conditions and, therefore, has a relatively large o...

Day or night telescope- draw tube inscription Photo Mugs This achromatic telescope has a wooden barrel and three brass draw tubes. The other brass fittings include a sliding eyepiece cover, of which the slide is missing. The objective lens cap is also missing. The makers name is engraved on the smallest draw tube as G Dixey London, referring to George Dixey, who is known to have been trading from 1809. The words Day or Night are inscribed on the same dr...

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Celestron 44102 400x Power Laboratory Biological Microscope $99.95 Celestron 400X Laboratory Biological Microscope. For entry - level microscopes, it's in a class of its own! Reveal the magic in everyday objects! The texture of each rock, the fragile wings of an insect, or the veins of a leaf... all magnified in magnificent detail. You open your child up to a whole new intriguing world from the moment they open the box. Dollar-for-dollar, it might be the best ent...

Orion SpaceProbe 3 Altazimuth Reflector Telescope $99.99 Orion's surprising little Spaceprobe 3 has been picked by independent reviewers as one of the best telescopes in its price class. Unlike similar telescopes seen in discount stores, Orion has refined the Spaceprobe 3 by paying attention to the little details, and that make this telescope a great value. The Spaceprobe 3 comes with an unusually complete set of accessories. The package includes two ...

Orion Observer 70mm Altazimuth Refractor Telescope $139.99 Our Observer 70 is the perfect telescope for that budding astronomer in your family. This scope excels in both quality and performance. Its 70mm multi-coated achromatic objective lens - focal length 700mm focal length (f/10) - gathers 36% more light than a 60mm. And it's made of glass, not plastic, as you'd find in many department store models. The optical tube is supported on a sturdy aluminum tr...

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Pentax 65809 PCF II 12x50 Waterproof Binocular $199.00 See what you might have been missing with the PENTAX PCF WP II series of binoculars. A perfect companion for dusk or dawn observation, these high-performance models come with large objective lenses for superior light gathering in even the lowest light conditions. The nitrogen-filled bodies are protected by a rubber covering that makes them waterproof, fog-proof, and fully submersible down to one m...

Celestron Short 70mm Rich Field Refractor Telescope With 400mm Focal Length $39.99 This Celestron rich field scope is compact and portable. The glass optics are fully coated for clear and crisp images. Great for a giant finder scope or very light and portable second scope. This handy little scope comes with a dove tail mounting bar that fits any CG5 type mount. Also works with any photo tripod. SPECIFICATIONS OPTICAL DESIGN: Refractor APERTURE: 70mm FOCAL LENGTH: 400mm FOCAL...

Carson MM-200 Carson Micromax LED 60X-100X LED Lighted Pocket Microscope $19.00 CARSON MM-200 MICROMAX LEDTM 60X-100X POCKET MICROSCOPE...

Tasco Essentials 8x21 Binocular (Black) $8.20 Ultra-light binoculars offer outstanding compact performance with rugged, rubber armor ideal for hiking, backpacking or bicycling. Features fully coated optics for brightness, 8X magnification with 21mm objective lens, rubber fold-down eyecups for eye relief. Designed to fold down into itself to become even more compact. Includes carrying case. Limited lifetime warranty....

Celestron 21061 AstroMaster 70 AZ Refractor Telescope $99.99 TE3) Celestron astromaster 70AZ scope...

Alert! Bright New Comet / How Many Solar-System Objects Can You See? / Elusive Brown Dwarfs Found at Last / The Lure of Edge-on Galaxies / S&T Tests 31 Eyepieces / Galileo Probes Jupiter (Sky & Telescope, Volume 91, Number 4, April 1996) ...

An essay on the genuine construction of a standard microscope and telescope: with the application of a prismatic or catadioptric eye-piece to refracting and reflecting telescopes, ... By B. Martin. $8.35 The 18th century was a wealth of knowledge, exploration and rapidly growing technology and expanding record-keeping made possible by advances in the printing press. In its determination to preserve the century of revolution, Gale initiated a revolution of its own: digitization of epic proportions to preserve these invaluable works in the largest archive of its kind. Now for the first time these hi...

Nikon 7216 Action 8x40mm Binoculars $62.00 New Nikon 7216 8X40 Action Birding Binoculars W/Case.Includes deluxe case, strap, instructions, and box..Aspherical eyepiece lenses with multi-coated prisms Quick central focus system 420-foot field of view at 1,000 yards Magnification: 8x Objective lens: 40mmLike the Actions with 50mm objective lenses, the 8x40 and 7x35 models in this ever-popular series have been updated with enhanced and ergono...

BARSKA 40070 Starwatcher Compact Refractor Telescope with Table Top Tripod And Carrying Case $59.39 An ideal entry-level telescope for amateur astronomers, the Barska Starwatcher 300-power telescope brings you closer than ever to the stars and planets. The refractor telescope is equipped with such features as coated glass optics for enhanced image brightness, interchangeable eyepieces with 3x Barlow lenses for increased viewing power, and smooth-functioning mounts. For good measure, Barska added...

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