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GSO Coma Free 8" F6 Dobsonian for photography

  • 49900
  • Save $ 90


Basic Manual for Focuser Adjustment & Optical Alignment

Coma Free Optics

This big GSO Dobsonian reflector features a 8" (203mm) diameter parabolic primary mirror with 94%-96% reflectivity.  Coma is an inherent property of telescopes using parabolic mirrors.  This results in an image that is not in the center of the field looking wedge-shaped. This causes stars to appear to have a cometary coma in traditional Dobsonian reflector.

Built in GSO Coma Corrector is optimized by 3 elements fully coated lens, providing pinpoint stars to the edge of the field with no increase in magnification.  We pursue the optical performance beyond everything. We provide the excellent optical performance with affordable price. 


The Advantage of Photography

There are several brands Dobsonian in market which you can not take a picture directly with.  Because of the short back focus, the focuser is not short enough for direct photography.  They are really designed for observing but not for photography.

Because of the GSO coma corrector extends extra 4" focal length, the direct photography is feasible only in our Coma Free system.


Sturdy and Reliable Construction

The telescope's f/6 optics and 1200mm focal length delivers great observing performance. The secondary mirror has a 62.5mm minor-axis and its alignment can be adjusted with a Philips head driver in perfect alignment for the best views possible. Our tube designed GSO Dobsonian looks not so fascinated compared with other movable truss constructed Dobsonian.  However, the optical axis of symmetry in tube constructed GSO Dobsonian is most reliable among all products.

Motion of the GSO Dobsonian in both altitude (up/down) and azimuth (left/right) is silky smooth thanks to azimuth high cost roller bearings, adjustable ball-bearing altitude trunnions. Tension of both altitude and azimuth motion axes can be adjusted easily, without using tools, to support heavy accessories on your GSO Dobsonian anytime.


Fabulous Focusing Mechanism

The GSO Dobsonian telescope features a machined, 2" Crayford focuser with dual-speed adjustment control. The fine-focus control knob allows you to dial-in details at a 10:1 ratio ultra-precise focusing. An included adapter allows use of both 2" and 1.25" sized telescope eyepieces, and both holders feature non-marring compression rings to keep eyepieces in-place without scratching.



Two telescope eyepieces are included: a big 2" 5-elements Superview 30mm focal length, and a 1.25" 4-elements Plossl 9mm focal length eyepiece. A handy eyepiece rack for the GSO Dobsonian base is included, which provides a convenient storage spot for your telescope eyepieces and other accessories. A 35mm-length 2" extension adapter is also included.

The included 8x50 finder scope is bright aiming tool for the 8" Dobsonian telescope. To reduce cool-down time, an included cooling fan can be plugged in (fan battery pack requires 8xAA batteries - not included) to help circulate air in the reflector optical tube for fast performance.


Product Content

Coma Free Dob 8" F/6 (White) telescope & Base in separated packages

35mm 2” CNC extension tube

Covers & battery case

2" Crayford focuser with 1/10 Micro transmission

8x50mm Finder Scope and Bracket

2" Coma Corrector

2” 30mm & 1.25” 9mm eyepieces

Laser Collimator

Free Shipping  in US mainland only


Other recommendation

Laser Collimator: This laser collimtor is quarantined to align a optical path less than 7m within 2mm bias. This is a quick and excellent tool to make sure all mirrors and focuser center symmetrically.  However, you still must pay attention to the unavoidable tolerance between the installation of the collimator and internal diameter of a focuser.    The collimator cots $49, but only $30 for the customer who has bought telescopes in our store.

Photography adapter: You need an adapter to connect a camera (M42 thread) to your telescope for photography.  We provide high precise, CNC quality, and multi-functional adapter in our store.

CPL eyepieces: CPL eyepieces is little expensive than camera adapter and eyepieces.  If you consider to buy extra eyepieces, the CPL eyepieces would be one of the best choice among them.  CPL eyepieces is not only a high quality eyepiece but an a camera  adapter with M42 thread on it. 


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