GSO 10" f/4 Imaging Newtonian telescope - for astro photography and rich field observation
This compact and affordable 250mm (approx. 10") f/4 Newtonian optical tube assembly (OTA) from GSO has fast optics for imaging extended deep-sky objects with a DSLR, webcam, or dedicated astronomy camera. Lightweight and easy to guide, this little Newtonian comes ready to go out of the box with a 3.25" Crayford-style focuser with 2" eyepiece holder, dual split-hinged mounting rings, an 8x50 straight-through finder, and an 8" Vixen/Synta-style dovetail plate.

Fast 10" f/4 Newtonian optics for wide-field imaging with DSLRs and a wide range of CCD and CMOS astronomy cameras
Fully and rigorously tested on site for cosmetics, mechanical operation, and optical performance by a master optician to ensure excellent overall telescope operation and customer satisfaction (an Agena exclusive service) 
Dual-speed 2" Crayford linear bearing focuser securely holds your camera and accessories with minimal wear and flexure
Includes 2" 35mm-long extension tube and 2"-1.25" eyepiece adapter
8" Vixen-style dovetail bar with dual split-hinged felt-lined mounting rings to protect tube finish
8x50 straight-through achromatic finder mounted on quick-release bracket
Center dot on primary mirror for quick and easy collimation
Solid rolled steel telescope tube with gloss white exterior finish and matte black interior finish to increase contrast and minimize thermal effects
Low noise, long-lifetime cooling fan on primary mirror cell powered by 8 AA batteries (not included)
 
Portable, Light Weight, and Economical
The GSO 250mm (approx. 10") f/4 imaging Newtonian offers a fast focal ratio that's ideal for capturing wide-field images of hundreds of celestial objects. The 1,000mm focal length keeps the tube length to a farily compact 38.2", making it easier to guide during extended exposures. It has a total weight of 34lbs-1oz (29lbs-12oz with OTA and focuser only). And with a price that's far less than a small ED refractor or Ritchey-Chretien scope, this OTA offers an economical alternative for beginning and advanced imagers.
 
Fast and Precision Optics
The precisely figured 10" f/4 primary mirror is made from BK7 optical glass for enhanced thermal stability. BK7 is far superior in thermal characteristics to soda lime float glass - the glass used in consumer products like cookware - that's used in many reflectors in this price range. The mirror is coated with enhanced aluminum to at least 92% reflectivity and coated with a protective layer of SiO2 (quartz) for durability. The primary mirror is mounted in a cell with six external push-pull collimation knobs on the back of the tube, and the center-marked primary makes collimation with a laser a snap.

With a cropped-sensor DSLR camera or an astronomy camera such as the ZWO ASI071MC-Pro with an APS-C sensor, this scope gives a wide field of view, more than enough to frame the brightest regions of extended deep-sky objects like the Andromeda and Triangulum galaxies, the Orion Nebula, and the Horsehead Nebula.
 
What's in the Box
250mm f/4 Newtonian optical tube assembly
3.25" Crayford-style linear bearing focuser with 2" eyepiece holder and 1.25" eyepiece adapter
8x50mm straight-through finder with bracket and base
Tube rings
Vixen-style dovetail rail
2" extension tube with 35mm extension
Front dust cover
No instruction manual is included
 
The precise 2" crayford focuser with 1:10 micro transmission and Accessories
We offer this Newtonian telescope with a 2" Crayford style focuser with integrated 1:10 dual speed transmission. This focuser works very precise even with heavy accessories like astro cameras. With a bit of experience, you can achieve accuracies around 0.08 mm which is sufficient even for very high resolution sensors.
 
Tube and Mounting Rings
The tube of this imaging Newtonian is made from rolled steel for good thermal stability and it's capped with end rings of die-cut aluminum for protection and rigidity. It includes a dust cap. The scope also comes with two split-hinged die-cast aluminum mounting rings with felt lining to protect the finish of the tube. These rings make it easy to rotate the tube to bring the focuser and finder to the most comfortable viewing position. The bottoms of the rings have threaded mounting holes for a Vixen-style mounting plate (which is included) or an optional Losmandy-style plate. The tops of the two rings each have two threaded M6x25mm holes that are 7.5" apart so you can install a separate dovetail to mount other accessories such as a guide scope.

The tube has an attractive outside gloss white finish and a matte black interior finish to reduce stray reflection and increase image contrast. The tube is 12" in diameter (12.1" at the end rings), 38.2" long, and it extends beyond the focuser to act as a shield to prevent stray light from entering the tube and reducing image contrast. The primary mirror cell also includes a low noise, long-lifetime cooling fan powered by 8 AA batteries (batteries not included).

TELESCOPE SPECIFICATION

TELESCOPE SPECIFICATION
Country of Manufacturing	TAIWAN
Optical Design	Parabolic Newtonian Reflector
Primary Mirror	254 mm Primary Mirror 94% reflectivity dielectrically coated/minimum 1/12th wave, BaK7 glass
Focal Length	1000mm
Focal Ration	f/4
Highest Practical Power	300
Faintest Steller Magnitude	14.7
finder Scope	8x50 Fully multi-coated achromatic finder with quick-release bracket
Primary mirror:	Parabolic primary mirror with 94% enhanced reflectivity coatings and quartz layer
Focuser	2" Crayford focuser with 1:10 dual speed transmission and reducer to 1.25", with 2" extension tube - to achieve focus with all kinds of eyepieces
Accepts Eyepiece Barrel Ø	50.8mm (2") to 31.7mm(1.25")
Mirror Cell	Primary mirror Cell with 12V Main mirror cooling fan
Secondary mirror:	63 mm diameter (minor axis) with 94% enhanced reflectivity coatings and quartz layer
Eyepiece 1.25" / 2" OD	OPTIONAL
Barlow Lens	OPTIONAL
Mount type	NO
Astro-imaging capability	Lunar Planetary & Deep Sky
Mounting Ring	Two mounting ring
Dove tail Bar system	Yes
Tube material	Steel
Tube dimensions	length 980 mm / diameter 310 mm
Weight, optical tube	15.5 kg including mounting ring and 8x50 finder
Shipping Weight OTA	Tube : Net weight - 17.5 Kg / Gross weight: 21 Kg
Shipping Carton Dimension 10" f4 OTA	103 cm x 52 cm x 46 cm

WARNING

This device focuses a lot of light.
Looking directly at the SUN through this device can result in partial or complete loss of vision.
For observing the SUN, we recommend you buy a 'Solar Safety Film' for this Telescope.

Buy 1000 OAKS Solarite Safety Film

Free Items [ Subject to Availability ]

• Collimination Tool (for Newtonian)
• 110 Messier Object Locator - A4 size front back colour print
• 109 Deep Sky CALDWELL Catalogue - A4 Size Front Back Colour Print
• Star Dial - Identifying Stars & Constellations
• Astronomical Telescope - User Guide
• The Moon Map Poster B/W chart unfold to 22"x26"
• Magnitude 5 Star Atlas Book