กล้องดูดาวสะท้อน GSO 8" f/5 Reflector OTA, Dual-speed Crayford Focuser 2" พร้อมตัวแปลง 1.25" adapter GS630

• ใช้กระจกคุณภาพสูงที่เกินคุณสมบัติ diffraction limited (ภาพที่ได้ถูกจำกัดด้วยกฏของฟิสิกส์เท่านั้น) ด้วยหน้ากล้องที่ใหญ่ถึง 8" ในราคาที่สุดคุ้มค่า
• เก็บแสงได้มากกว่ากล้องดูดาวขนาด 6" ถึง 78% เหมาะกับการส่อง DSO เช่น กาแลกซี่ nebula กลุ่มดาว (star clusters) เป็นพิเศษ กระจกเคลือบด้วย Quartz เพื่อความคงทนนับ 10 ปี
• ความไวระบบภาพ F/5 เหมาะกับการถ่ายภาพ DSO เช่น กาแลกซี่ nebula กลุ่มดาว (star clusters) 
• มาพร้อม Crayford focuser แบบ 2" (ปกติกล้องราคานี้จะมาพร้อม Rack and Pinion Focuser ขนาด 1.25" ซึ่งถูกและแข็งแรงน้อยกว่ามาก)
• Dual Speed focuser สามารถปรับฟอกัสที่ความละเอียดเพิ่มขึ้นในอัตราส่วน 10:1 เพื่อให้ได้ภาพที่ฟอกัสชัดที่สุดเท่าที่เป็นไปได้
• รองรับ Eyepiece และอุปกรณ์ขนาด 2" ซึ่งเป็นอุปกรณ์ที่ใช้ในหอดูดาวขนาดใหญ่ เพื่อรองรับมุมภาพที่กว้าง ใช้สบายตา มาพร้อมตัวแปลง 1.25" จึงรองรับทั้ง eyepiece และอุปกรณ์ 1.25" ด้วย
• ในกล่องรวม Extension tube 35mm, กล้องเล็งขนาดใหญ่ 8x50mm แบบตรง, tube ring และ mounting bar มาตรฐานพร้อมยึดกับขาตั้งกล้องดูดาวสมัยใหม่ได้ทันที
• รองรับอุปกรณ์เสริมมาตรฐานเช่น eyepiece, ฟิลเตอร์, barlow lens, อุปกรณ์ถ่ายภาพดาราศาสตร์แบบต่างๆ และอื่นๆอีกมากมาย
• GSO เป็นผลิตภัณฑ์คุณภาพสูง งานกลึงละเอียด ควบคุมด้วยระบบคอมฯ (CAM) ผลิตในไต้หวัน; ประกัน 2 ปี

โปรดทราบ:  กล้องสะท้อนแสงในราคาใกล้เคียงมักใช้ฟอกัสเซอร์ Rack and Pinion (R&P) ซึ่งถูกกว่าและไม่แข็งแรง และรองรับแต่ Eyepiece ขนาด 1.25" เท่านั้น และไม่สามารถฟอกัสได้เมื่อนำกล้องถ่ายรูปมาต่อ ทำให้ไม่สามารถถ่ายภาพดาราศาสตร์ได้  กล้องรุ่นสะท้อนของ GSO อาจเป็นกล้องเพียงไม่กี่รุ่นในตลาดที่ใช้ทั้งฟอกัสเซอร์แบบ Crayford ขนาด 2" และรองรับการถ่ายภาพดาราศาสตร์และดูดาวในตัวเดียวกัน ในราคาที่ต่ำพอจะเป็นเจ้าของได้

The GSO GS630 houses a big 203mm parabolic mirror with 78% more light grasp than a 6" mirror and 216% more light than a 4.5" Dobsonian, for brighter, more detailed views of night sky curiosities. GSO mirrors are extremely well figured and are guaranteed to be difraction limited - for sharp high contrast images of nebulas, galaxies, and star clusters. Planetary images are also sharp and crisp, although the included neutral density moon filter is often required to allow glare-free observing. The mirrors are overcoated with quartz for long life.

Under dark skies, the Orion Nebula becomes a glowing complex of filaments, filling the wide 1.7° field of the supplied 2” eyepiece. Globular clusters are often resolved to the core. Messier, NGC, and IC objects show detail and structure never visible in the smaller telescopes that are more common in this price range. The diffraction limited quality optics from GSO will at the same time offer razor sharp images even at high magnifications. Planets and the moon will be seen in great detail. The visibility of details is not limited by the telescope, but rather by observing conditions! As with any serious telescope, the performance of the 8” GS630 on faint objects will be improved by a dark sky observing site.

While it is in deep space observing of galaxies and nebulas from a dark sky observing site that this 8” GSO Dobsonian excels, significant planetary and lunar observing is also well within its capability. Given suitably good seeing, Encke’s Division and other minor features in Saturn’s rings occasionally become visible in the 8” GS630, as does Saturn’s faint crêpe ring. Low contrast banding and details in Saturn’s atmosphere begin to make themselves apparent, as well. Lunar features less than one mile across become visible, while Jupiter’s four Galilean moons start to show as tiny discs. Small details in the atmospheres of Jupiter and Saturn and on the surface of Mars reveal themselves at high powers given suitably good seeing.

The 2" Dual-Speed Crayford Focuser

Most instruments of this size only have a 1.25" focusers. This is OK for visual use, but limits photographical capability. The GSO Newtonian has a 2" Crayford focuser and sufficient back focus to be able to reach focus with DSLR cameras. With the supplied 2" extension tube you will also reach focus with regular eyepieces providing the best of both worlds. The extension tube, and both the 2” eyepiece holder and the 1.25” adapter use non-marring soft brass compression rings to hold eyepieces in place, rather than simple thumbscrews that can scratch your eyepiece barrels. The machined aluminum focuser has dual coarse focusing knobs for smooth and precise image control with either hand. There is a separate 10:1 reduction ratio microfocus knob for ultra-fine focusing at high magnifications. The ribbed focus knobs are easy to operate, even while wearing gloves or mittens in cold weather.

Parabolic Mirror

With a 8” (203mm) diameter, 1000mm focal length, f/5 focal ratio. Parabolic mirror. The mirror is made of B270 “water white” optical crown glass that is free of internal stress and striae. B270 glass is equivalent to BK7 in performance and optical quality. The thermal stability of B270 glass is generally better than the soda lime float glass used for the mirrors of most reflectors in this reasonable price range. The mirror is ground and polished under computer control for guaranteed diffraction limited performance, coated with 94% reflectivity aluminum, and overcoated with a protective layer of silicon dioxide (quartz) for long life.

Primary mirror cell

Fully adjustable 3-point flotation system metal cell holds the primary mirror. The open frame of the cell allows the mirror to cool down to ambient temperatures quickly, so you can start observing sooner. Large hand-tighten color-coded push-pull collimation and collimation lock knobs make it easy to collimate the primary mirror with no tools required.

Ease of collimation

The GSO GS630 also allows you to calibrate your mirrors to obtain the highest quality images that the telescope mirror is capable of. Use a philips (cross-head) screw driver to keep both primary and secondary mirrors in alignment. Such screws makes it easy to get the best out of your GSO GS630 telescope which has great reputation for its best-in-class mirrors.

For the primary mirror, a fully adjustable 3-point flotation system metal cell holds the primary mirror. The open frame of the cell allows the mirror to cool down to ambient temperatures quickly, so you can start observing sooner. Large hand-tighten color-coded push-pull collimation and collimation lock knobs make it easy to collimate the primary mirror with no tools required.

Finderscope and bracket:

8 x 50mm straight through fully-multicoated dark crosshair achromatic design. The finder has a long and comfortable 13mm eye relief. It focuses by loosening the trim ring behind the objective lens cell, screwing the lens cell in or out to focus, and tightening the trim ring to lock in the correct focus.

The 8 x 50mm finderscope mounts in a quick release bracket that slips into a pre-installed metal mounting shoe beside the focuser. The bracket is held in place in the mounting shoe by a single large hand-tighten chrome-plated knob that maintains the finder’s collimation, even if the finder is removed between observing sessions.. The bracket has two hand-adjust collimation screws that work in conjunction with a third spring-loaded post in the bracket. This makes collimation faster than the traditional three- or six-screw collimation methods used with conventional finder brackets.

The GSO 8" f/5 newtonian is a good telescope for astrophotography:

The Newtonian Telescope is ready for astrophotography with many good features for beautiful astrophotos.

• Fast f/5 ratio lets in more light allowing shorter exposure
• 2" Crayford focuser with precise movement also suitable for heavy cameras
• Dual-speed focuser allows extra fine focusing mode at 10:1 ratio so that objects stays in sharpest focus possible
• Enough back focus for standard coma correctors
• Big illuminated field - good for standard DSLR cameras
• 94% encanced coating on main- and secondary mirror for a brighter image

Other included accessories:

A 35mm extension tube for visual use. Can be expanded by adding more accessories (eyepieces, filters, barlows, astrophotography adapters, etc.)

Specifications

What's in the box:

• Newtonian telescope - optical tube
• 8x50 achromatic finderscope
• aluminium rings with M6 connection thread on both sites
• Mounting bar
• 2" 35mm extension tube for visual observing
• 2" to 1.25" adapter for supporting 1.25"  eyepieces and accessories

GSO is a leader in optical telescopes and accessories and their products have been sold for years by the "Big Three" (Meade, Celestron and Orion) under their own brand names. GSO telescopes and accessories are also sold under different names world-wide; Zhumell (USA), Apertura (USA), TPO (USA), Teleskop Service (Germany), Sky Optic (France), Antares (Canada), Astronz (New Zealand), and more than a dozen more brands too many to name. GSO is known for their high consistency in quality control, low defect rate, and their Taiwanese-based manufacturing scores closer to Japan in quality than other telescope manufacturers which mostly manfacture thier scopes in Mainland China. Give these telescopes a try - you will not be disappointed!