Telescope Orion 10-inch f/3.9 Newtonian Astrograph

Orion 10-inch f/3.9 Newtonian Astrograph is by far the largest reflector type of telescope that is optimized for capturing astrophotographs from deep-sky. It is the telescope’s parabolic primary optics with a very fast focal ratio that enables it to deliver enviable wide-field and deep-space imaging performance. You get to see stunning details of even faint nebulas and galaxies with only limited exposure when you take photographs through this large-aperture astrograph using either a DSLR camera or a CCD imager. Further, the images will not only be incredibly bright but also very crisp. Above all, the well-designed instrument is highly affordable.

Telescope Orion 10-inch f/3.9 – Key Features

  1. The Newtonian Astrograph boasts of the largest reflector optimization which is best suited for astrophotography.
  2. It comes with a 10 inch parabolic primary optics. In addition to the mark at the center point of the primary mirror, it is provided with three numbers of easy-grip collimation knobs to make optical alignment not only easy but also precise.
  3. It has an extremely fast focal ratio of f/3.9.
  4. The telescope’s secondary mirror with its 82-millimeter minor axis enables full-field illumination when using modern DSLR cameras and CCD imager. The light drop-off at the APS-C sized sensors is less than 8 percent. Further, the adjustable four-vane holder of the secondary mirror comes with spider vanes that are one millimeter thick so that the diffraction effects are minimized in images.
  5. Both the primary and secondary mirrors are provided with an aluminum coating to enhance reflectivity. They provide 94 percent reflectivity.
  6. The additional tube length of 7.5 inches provided in front of the focuser helps to block off-axis light intrusion. This is to ensure that the image contrast remains optimum. The sturdy two-inch, low profile, dual-speed (11:1) Crayford focuser allows you to experience ultra-fine focus. It comes with a drawtube lock knob and drawtube travel length of 38 millimeters. Further, the steel reinforcement plate fitted within the 38.6″ long tube directly below the focuser prevents flexure, even if you attach heavy imaging gear.
  7. It is recommended that you have a coma corrector (optional item) in order to achieve better flat-field imaging performance as in the case of all Newtonian telescopes. Standard accessories included in the box are:
    • 1 no. Orion 10″ f/3.9 Newtonian Astrograph
    • 1 no. 9 × 50 finder scope with bracket
    • 1.25 inch and 2 inch extension eyepiece adapters
    • 2 nos. hinged tube rings made of cast aluminum
    • 1 no. 12 Volts DC fan for cooling down the primary mirror fast. The fan works on 8 AA batteries or a 12 Volt power supply. The batteries and power supply are not included as standard accessories.
    • Collimation cap
    • Dust caps
    • Starry Night astronomy software (Special Edition)
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Telescope Orion 10-inch f/3.9 – Specifications

  • User level – Intermediate
  • Optical design/type – Reflector/ Parabolic
  • Mount type – Optical Tube without Mount
  • Astro-imaging capability – Lunar, planetary and long exposure
  • Optical diameter – 254 millimeter
  • Optical quality – Diffraction limited
  • Optical tube length – 38.6 inches
  • Optical tube weight – 25.5 pounds
  • Finder scope – 9×50
  • Focuser – 2 inch dual-speed Crayford
  • Focal length – 1000 millimeter
  • Focal ratio – f/3.9
  • Resolving power – 0.46arc*sec
  • Lowest and highest useful magnification – 25× and 300×
  • Highest theoretical magnification – 500×
  • Limiting stellar magnitude – 14.7
  • Secondary mirror obstruction – 82 millimeters; 32 percent by diameter and 10 percent by area
  • Glass material – Glass with low thermal expansion
  • Material of tube – Steel
  • Mirror coatings/over-coatings – Enhanced aluminum and Silicon Dioxide
  • Warranty: Limited warranty for one year against material defects or workmanship from the date of purchase. The warranty is applicable only in the case of original retail purchase.
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Telescope Orion 10-inch f/3.9 – Pros and Cons

A little bit of research on the Internet shows that a majority of the users are very happy with the Orion 08296 10-inch f/3.9 telescope. Most of them have also noted that they will recommend this astrograph to others. Some of the pros and cons of this telescope, as brought out by those who have actually used the instrument, are listed below to help you make an informed decision.

The 10 inch mirror of Orion 08296 10-inch f/3.9 telescope collects an incredible amount of light. This means that the exposure time required for capturing images are extremely low. This is to say that excellent and bright images of galaxies and nebulae can be obtained with relatively short exposure times. Three 30 seconds exposures provided impressive results on Spiral Galaxy Messier 51.
A good quality auto tracking mount (equatorial or azimuthal) has been helpful in producing great results. Further, a lot of things can be done, especially with an equatorial mount. 
It has been observed that it is possible to achieve good results with a DSLR camera or a CCD imager.
The focus is precise though some adjustment is required to optimize movement. 
This easy-to-use telescope makes it easy for you to learn astro-imaging. Further, the large mirror enables you to detect even faint objects. 
A cooling fan is attached to the rear side of primary mirror cell of f/3.9 Newtonian Astrograph. This helps to reduce the time duration taken by the primary mirror to establish a thermal equilibrium with the ambient air.
The telescope has a very pleasing appearance and is very competitively priced. For the price you pay, it provides great value through its phenomenal features.
One year limited warranty.
Finally, there is no disagreement among users as regards the optical and mechanical quality, ease of assembly and use, and the value that the Orion 08296 10-inch f/3.9 Newtonian Astrograph reflector telescope offers to its users, but it is a little bit bulky as well as heavy. It takes a little bit of effort for you to move it around.

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Telescope Orion 10-inch f/3.9 – Final Thoughts

The reflector type telescope Orion 10-inch f/3.9 Newtonian Astrograph is a value for money astrophotography instrument. It can even be used as a visual telescope as well. It has a large aperture (10 inches) and a very fast focal ratio which enables you to enjoy great views of objects far away in space. You can enjoy fantastic views of the moon, planets, and sparkling star fields using both the 1.25 inches and 2 inches telescope eyepieces.

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