Orion #8296 10" F/3.9, #8297 8" F/3.9 Visual Observing with the f/3.9 Newtonian Astrograph

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drawtube

Reflection of primary mirror clip

a.

Reflective surface

Primary mirror

of collimation

center mark

cap

 

b.c.

d.e.

Figure 8. Collimating the optics. (a) When the mirrors are properly aligned, the view down the focuser drawtube should look like this. (b) With the collimation cap in place, if the optics are out of alignment, the view might look something like this. (c) Here, the secondary mirror is centered under the focuser, but it needs to be adjusted (tilted) so that the entire primary mirror is visible. (d) The secondary mirror is correctly aligned, but the primary mirror still needs adjustment. When the primary mirror is correctly aligned, the center “dot” of the collimation cap will be centered, as in (e).

cal tube in front of the focuser. Both the 8" and 10" models have added length in front of the focuser, compared to a stan- dard Newtonian, to prevent any possibility of incoming light from impinging directly on the secondary mirror or entering the focuser drawtube. The baffle rings and the interior of the optical tube are both painted flat black to further absorb stray light. These enhancements ensure the best possible contrast when observing and photographing faint celestial objects.

Visual Observing with the f/3.9 Newtonian Astrograph

The 8" and 10" f/3.9 Newtonian Astrographs are optimized for photographic imaging, but they can also be used of visual observing of ccelestial objects. (Because the field of view in a Newtonian reflector is rotated from right-side-up, this type of telescope is not recommended for terrestrial observing.) The tall 1.25" eyepiece holder adapter that comes installed in the focuser from the factory should allow you to achieve focus with most 1.25" telescope eyepieces (Figure 7).

For 2" eyepieces, you will likely have to use a 2" extension adapter to achieve focus with a 2" eyepiece. Two such adapt- ers are included with your telescope (Figure 7). One is a thread-on adapter that adds 30mm of extension, the other is a slip-in adapter that adds 36mm of extension. You may need one or the other adapter depending on the amount of exten- sion required for your eyepiece.

To install the thread-on 2" extension, first remove the 2" accessory collar on the focuser drawtube by turning it coun-

terclockwise until it comes off. Then thread the 2" extension adapter onto the focuser drawtube until tight. Insert a 2" eye- piece into the extension adapter and secure with the two thumbscrews. To install the slip-in 2" extension adapter, just insert its tapered base into the 2" accessory collar of the fo- cuser, then tighten the two locking thumbscrews to secure the adapter in place.

Collimating the Optics (Aligning the Mirrors)

Collimating is the process of adjusting the mirrors so they are aligned with one another. Precise collimation of the optics is especially critical for fast Newtonian optics such as in the f/3.9 astrographs. If the mirrors are even slightly misaligned, image quality will suffer. So you should check the collimation before every observing or imaging session, to make sure it is dead- on. The process of collimation is a relatively easy and can be done in daylight or darkness.

Your telescope’s optics were collimated at the factory, and should not need much adjustment unless the telescope was handled roughly in transit. To check collimation, remove the eyepiece and look down the focuser drawtube. You should see the secondary mirror centered in the drawtube, as well as the reflection of the primary mirror centered in the sec- ondary mirror, and the reflection of the secondary mirror (and your eye) centered in the reflection of the primary mirror, as in Figure 8a. If anything is off-center, proceed with the following collimating procedure.

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Contents OrionTelescopes.com Orion 8 and 10 f/3.9 Newtonian AstrographsDVD Parts ListFine Focus Getting StartedAttaching the Telescope to a Mount Dual-Speed Crayford FocuserAligning the Finder Scope Focusing the Finder ScopeOperating Your Orion f/3.9 Newtonian Astrograph Attaching the Finder ScopeMirror Cooling Fan Fan InstallationUsing the Cooling Fan Cooling the TelescopeAttaching a Dslr Camera Attaching a CCD CameraRemoving the Piggyback Camera Adapter from the Tube Ring Collimating the Optics Aligning the Mirrors Visual Observing with the f/3.9 Newtonian AstrographPreparing the Telescope for Collimation Adjusting the Secondary Mirror’s Axial PositionCollimation Cap Primary Mirror Center MarkAdjusting the Secondary Mirror’s Rotational Position Adjusting the Secondary Mirror’s Radial PositionAdjusting the Secondary Mirror’s Tilt Star-Testing the Telescope Care & MaintenanceAligning the Primary Mirror Cleaning Mirrors Specifications One-Year Limited Warranty

#8296 10" F/3.9, #8297 8" F/3.9 specifications

The Orion #8297 8" F/3.9 and #8296 10" F/3.9 reflect the latest innovations in astronomical technology, designed to meet the needs of both amateur and professional astronomers. These telescopes are renowned for their impressive optics, portability, and user-friendly features, making them ideal for deep sky observation and astrophotography.

The Orion #8297 8" F/3.9 features an 8-inch aperture, which allows for a remarkable light-gathering capacity, making it suitable for observing faint celestial objects. With a fast focal ratio of F/3.9, this telescope enables astronomers to capture stunning images of galaxies, nebulae, and star clusters with minimal exposure times. The telescope’s well-constructed primary mirror is made from high-quality glass, ensuring sharp and detailed views of the night sky. Additionally, the dual-speed 2” Crayford-style focuser enhances focusing precision, allowing users to achieve fine adjustments with ease.

On the other hand, the Orion #8296 10" F/3.9 elevates the observational experience with a larger 10-inch aperture. This increased size further enhances light-gathering ability, resulting in even clearer images of distant objects. Like its 8-inch counterpart, the F/3.9 focal ratio makes this telescope particularly advantageous for astrophotography, enabling users to shoot spectacular deep-sky images efficiently. The telescope is constructed with a sturdy, fully adjustable mount that ensures stability while tracking celestial objects, even during high-magnification viewing.

Both models come equipped with adjustable finderscopes, which assist in locating objects in the vast night sky, and they include a set of high-quality eyepieces that provide a range of magnifications to suit different observation needs. Furthermore, the lightweight design of both telescopes allows for easy transport to various observing sites, making them versatile tools for astrophotography enthusiasts and casual observers alike.

In summary, the Orion #8297 8" F/3.9 and #8296 10" F/3.9 are excellent telescopes that combine advanced optics with user-centric design. Their strong performance, portability, and innovative features make them perfect choices for anyone looking to explore the wonders of the universe, from novices to seasoned astronomers.