Used Orion 100ED OTA and rings w/RACI, glass solar filter + focus motor

This is an Orion ED100 OTA in very good condition.  It is probably about 15-20 years old; the glass is clean and clear, and the tube is relatively unmarked, although the color has faded a bit with age.  If you're looking for a big step up from the views through your achromat, or if you want some decent glass to do some astrophotography, this is a great bargain.  

It includes a glass solar filter for the scope (a $xx value), an 8x50 RACI finder (a $xx value), a film solar filter for the finder (a $10 value), and a focus motor (a $25 value).  

This is available for pickup in our showroom.  Or, we can ship this to you for a $29 shipping charge.  There are no returns on this item.  

The 4 inch (10cm) Apo refractor has long been regarded as the most perfect single telescope providing the best compromise of portability and usefulness in amateur astronomical applications. The 4" Apo can: 

• 1. deliver the light gathering and high contrast resolving power necessary to reveal many celestial objects with a very natural almost three dimensional appearance,
• 2. can provide a wider span of Field of View than any Reflecting or Catadioptric design with an aperture that can show similar detail, and
• 3. can cross to above the critical 200x threshold of planet and lunar observing that reveals subtle details and changing features from night to night.

The 100mm ED approaches 200x in term of light gathering power over the unaided human eye and this is about a 1.56X increase over the throughput of its smaller cousin the Orion 80mm ED. It is possible to glimpse the entire "Messier Catalog" of deep sky objects even from reasonably moderately light polluted suburban skies. One of the finest advertisements ever published for the 4 inch Apo telescope is the book Deep-Sky Companions: The Messier Objects by Stephen O'Meara. To produce the highly detailed drawings of these deep space objects Stephen observed with an older generation TeleVue "Genesis" telescope of 500mm f5 with Fields of View approaching 5 degrees! This book is among the best advertisements for the versatile, readily transportable fast 4 inch (10cm) refracting telescopes. He equipped the telescope with only a modest selection of accessories: TeleVue 22mm "Panoptic" eyepiece 23X, 2.85 Degrees Actual Field of View), a 7mm Nagler eyepiece (71X, 1.08 AFOV), and a TeleVue Barlow lens to increase the magnification by 1.8X. The 100mm ED views can approach those shown in O'Meara's book although it can not attain as wide a field of view as the Genesis, but for many who seek their first practical 4" Apo the 100mm ED will do nicely and the .

The 100mm ED can be used for a variety of applications including:

• Astronomy
  • versatile low to medium power visual telescope
  • photo-guide telescope
  • astrograph (with Field Flattener Telecompressor better than 3 degrees!)
• Terrestrial
  • Low Power, Wide Field Terrestrial observing
  • Use as a versatile Ultra-Telephoto Lens

ED Glass the air spaced doublet objective lens of the 100 mm ED is designed to provide precise optical color correction, and it is multicoated to improve contrast and transmission across the visual spectrum. The objective lens incorporates an Extra-Low Dispersion Fluorocrown FPL-53 extra-low dispersion "ED" optical glass from Japan; this is a glass crown element developed under laboratory conditions. Colors of the spectrum have differing wavelengths, to see this notice how in a normal optical glass prism the red and blue rays are bent at slightly different angles as they pass through. This dispersion results in color fringing that when looking through a telescope or telephoto lens usually appears as a slight violet halo around one object that contrast one against the other, and this can cause an overall lack of sharpness. In camera normal and wide-angle lenses this is imperceptible or can be corrected with other techniques, but telescopic lenses magnify the variation in focus between red and blue light rays. So the camera lens making companies (Carl Zeiss, Nikon, and Canon) pioneered Extra-Low Dispersion glasses and Fluorite crystal technologies to solve this problem. This ED glass material provides reduced chromatic aberration over similar f ratio achromatic designs in portions of the spectrum from the D (yellow), through C (red), F ( blue) and G (purple) Fraunhofer lines. 

What does it do? the Apochromatic refractor has been the traditional choice of visual astronomers. The combination of thermal stability, best view per pound of telescope, clear high contrast images, and apparent brightness can surpass more bulky designs such as the 8" Catadioptric and Newtonian telescopes. And the versatility of field of view and range of magnification is unrivaled by all other telescope designs.

This portable telescope provides stunning lunar and planetary observing; it can clearly reveal the major changing features on several planets through out observing seasons. You may imagine you are seeing details on the moon as if you were in orbit - even though the smallest object you could see with this telescope will actually be about 6 kilometers in diameter! And yet it is so compact and lightweight that a child can manage it.

The focal length of the 100mm ED is made even shorter, and the image quality improved with the optional focal reducer offered by Company Seven to our 100mm ED customers. This photograpic accessory delivers a wider field of coverage at f7.2 for terrestrial or astrophotography.

left: Orion ED telescope locking 2" Focuser and Reducer to 1.25". Notice the innovative arrangement of the Focuser Lock, this prevents marring the drawtube as is common with many other telescopes (52,574 Bytes).
Click on image to see enlarged view (88,227 bytes)

2 inch Focuser aside from good performance at higher magnifications the telescope is quite at home sweeping the Milky Way, or Comet hunting. This is an easily manageable telescope with the unobstructed 100mm light gathering power and fields of view to recognize many of the popular bright deep sky objects. Tease subtle details out of the Great Nebula in Orion, see the spiral nature of the Andromeda Galaxy. Seek out more deep-sky wonders including Star Clusters, and Planetary Nebulae, etc. Try a TeleVue 55mm Plossl eyepiece on for size, working at 16x provides a true field of 2.9 degrees. The combination of field of view and light gathering power will make hunting the large deep sky objects very rewarding, even more so with optional light pollution rejection filters. Or take the plunge into awesome perfection of the TeleVue 35mm Panoptic at 26X showing 2.45 degrees - suitable for astronomy and nature watching, with a view that is crystal clear across the entire field of view!

Notice the innovative arrangement of the Crayford style Focuser and Lock; this a low maintenance friction drive which eliminates the conventional focuser's use of a Rack and Pinion and need for lubricants. The adjustable set screw applies pressure to the Focuser Pinion to attain the proper adjustment of the friction control, this adjustment is critical. The downside of this arrangement is that it requires a bit of practice for someone used to working with a conventional rack and pinion focuser.

100mm ED telescope lightweight, yet adequate mechanical construction of metal and aluminum:

• Machined Aluminum, Black Anodized Front Cell
• Cast Aluminum, Gray Textured Painted Focuser
• Rolled Steel, Metallic Gray Painted Optical Tube
• Fully Baffled with interior finished in AR Black
• 2" diameter rack and pinion focuser. Moves with smoothness and precision, with no hint of backlash or play
• Focuser draw tube includes reducer to accept furnished 1.25" (31.7mm) accessories
• Focuser tension adjusting/locking screw permits the user to secure focus with heavy loads attached (such as a film or CCD camera) so that focus will not accidentally change over the course of an exposure or viewing session
  
• Dew Shield - slip on and easily removed
• Slip on Lens Cover with 52mm diameter on axis Aperture Stop
• 8x50 RACI Finder with Quick Release Bracket and film solar filter