OPT 8" f/9 Planet Pro Dobsonian Telescope

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OPT 8" f/9 Planet Pro Dobsonian Telescope
Item # OS-8DOB
  • Do you love the low-tech simplicity of a Dobsonian but want the higher contrast images of a longer focal length system?
  • The OPT 8" Pro Planet Dobsonian Telescope has a focal ratio of f/9 and comes with a small 1.25" secondary for APO-like contrast.
  • A four pole truss system makes the OPT Pro Planet Dob easy to transport, even for smaller cars!
  • The OPT 8" Pro Planet Dobsonian Telescope has a nicely finished Birch mount with real Ebony Star and Teflon bearings offer stability and smooth motion in both altitude and azimuth.
  • Comes with 2" 2-speed Crayford focuser, 1.25" adapter, 30mm SuperView eyepiece, Telrad, dust caps, truss carry bag and light shroud.


OPT 8" f/9 Planetary Dobsonian Telescope

The 8" f/9 Pro Planet Truss-Tube Dobsonian was custom-designed and created for OPT by Discovery Telescopes. We wanted something that was easy to transport but that produced those beautiful, high-contrast views that everyone loves so much.

We started with the most important part of any telescope...the optics. Our diffraction-limited 8" f/9 primary mirror is made in the USA of Pyrex, and is multi-coated for bright, sharp images of the planets, the Moon, and deep-sky objects. The mirror is center-marked.

The secondary mirror is small, with a mere 15.6% obstruction, to increase the contrast, and the spider is curved to eliminate diffraction spikes on bright stars and planets. The tube assembly is made up of two thermally stable Sonotube sections (upper and lower), and they are held in place with four truss poles. A truss tube carry bag is included with your OPT Planet Pro Dobsonian, and so is a light shroud and dust caps.

The Dobsonian base is made of Baltic Birch, and comes with real Ebony Star and Teflon bearings for smooth motions across the sky. The telescope comes with adjustable side bearings to allow the balancing of heavy eyepieces.

The focuser is a 2", two-speed Crayford-style model with compression ring fittings, and comes with a 1.25" adapter. Other accessories include a Telrad finder, 2" 30mm SuperView eyepiece, and as mentioned earlier, dust caps, light shroud, and truss carry bag.

OPT 8" f/9 Planetary Dobsonian Telescope Specifications...

  • Tube Diameter is 9.5"
  • Tube Length in Travel Mode - 40.25"
  • Tube Length in Observing Mode - 76"
  • Tube assembly weight is 31 pounds
  • Mount Weight - 21 Pounds
  • Dimensions - 28.25 x 22 x 16 inches
OPT Product Number: OS-8DOB
Additional Information

Additional Information

Manufacturer OPT
Telescope Series Discovery PDHQ
Optical Design Newtonian Reflector - Open Truss
Mount Type Dobsonian Cradle
Warranty 1 Year Warranty
Telescope Aperture 8"
Telescope Focal Length 1828mm
Telescope Focal Ratio f/9
Optical Coatings Aluminum
Limiting Stellar Magnitude 14
Tube Color or Finish OPT Deep Ocean
Finder Included Telrad
Eyepiece(s) Included 30mm SuperView
Optical Tube Weight 31 lbs.
Total Telescope Weight 52 lbs.
Length of Optical Tube 76"

Customer Reviews 1 item(s)

Heres a superior reflector...
I have an 8 f/9 custom by another company. I was delighted to find that the same optical configuration that has shown me so much has now been introduced as a product line at OPT.

Heres what the ad doesnt mention but you'll find out...

The smaller secondary under16% produces such clean contrasty stars by putting less light in the diffraction rings that you WILL see fainter stars than a compareble aperture at F/4 or f/5.

Detail on Jupiters face in the best seeing is an overload of contrasts with swirling patterns of belts, eddies, festoons, spots and so on being so overwhelming you cant draw it.
Im an artist - no you cant draw that much detail accurately and fast enough before it all shifts. On averege nights the advantage is still there, but on great nights, literally, you will be speechless.

Saturns Titan reveals as a disc.

Doublestars beyond the Dawes Limit are clearly made out. Elongated doubles of differing magnitudes are seen breathtakingly.

Fine planetary nebula benefit from the high contrast at high magnifications revealing disc-like forms easier than faster systems when the sizes approach 5. Central stars show fantasticaly, again, due to the very high contrast diffraction patterns.

Lunar mountain ranges bristle with details so rich it can be difficult to seperate one peak from another as the overwhelming sight comes at you in one riveting texture of impossibly tight points of light and dark. You cant describe it and Ive never seen it imaged.

Globular clusters are especially suited to the F/9 due to again, high contrast diffraction patterns putting more light in the spurioys disc than the surrounding rings. As a result the wealth of stellar richness seen in these objects bely the apertures size. The needle spiked points of light in dense richness of chains, sheets and dazzeling cores is tremendous. Open Clusters can be just as moving. Even obscure NGC open clusters you may never have heard about suddenly dazzle with the perfection of the finestly gleaming points of light, you keep increasing the magnification to even believe it.

This scoe will redefine what you thought was possible with an 8 aperture.
1= Houston, We Have a Problem & 5= It's Out of This World
Review by Pete / (Posted on 1/7/2012)
Included Items

Included Items

  • OPT 8" f/9 Planetary Dobsonian Telescope
  • 2" 2-speed Crayford Focuser
  • 1.25" Adapter
  • 30mm SuperView Eyepiece
  • Telrad
  • Dust Caps
  • Truss Carry Bag
  • Light Shroud
Questions & Answers

Product Questions

Why can't you just build this in a solid tube? The weight is going to be minimal. The solid tube Discovery F7 is 17 lbs. This might weigh in at 21 lbs. There are grave concerns on astronomy forums about the stability of this scope with the truss design.
Is it possible to add motor drive tracking to this mount?  With high powers used for planetary study, keeping the object in view would be critical for me.
Would a 10" f/7.5 Planet Pro be possible with a similar scaled up 4 tube truss design?
Who makes the mirror for this scope?
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