TPO 6" f/6 Newtonian Reflecting OTA Telescope

  • Price:
  • Sale
  • $179.10
  • Regular price $199.00

Free Shipping

limited time black friday 0% apr - see if you qualify!

Already have gear? Trade it in for cash or new equipment.

Accessories Added

  • Aperture: 6 inches
  • Focal Ratio: f/6
  • Focal Length: 916mm
  • White rolled steel exterior, flat black interior for higher contrast


TPO 6" f/6 Newtonian Reflecting OTA Telescope

The 6-inch f/6 Imaging Newtonian Telescope OTA and Focuser by Third Planet Optics (TPO):


If you are looking for a telescope that does a great job of imaging but doesn't come with the cost of a Ritchey-Chretien, check out the TPO Imaging Newtonian line of telescopes! All of our Imaging Newtonian optical tube assemblies, offered in apertures from 6 inch - 12 inch, have very fast optics for the widest fields possible. Image with a DSLR or small webcam all the way up to large sensor CCD cameras with these inexpensive yet effective Newtonians.

The optics on all TPO Imaging Newtonians consist of a parabolic primary mirror and an elliptical secondary, or diagonal. The mirrors are made from B270 white water optical crown glass, which is more thermally stable than glass traditionally used on other reflectors. A 91% aluminum coating is applied, and then over-coated with a layer of quartz for the ultimate in durability. The primary mirror cell is very sturdy, and has six collimation knobs that can be adjusted by hand with a push or pull of the knob. Collimation is made even easier due to the center spot marked on the primary mirror. The diagonal mirror is held in place with a thin four-vane spider.

There's a perfectly centered dot in the middle of the primary so you know exactly where your laser collimator should point. You stick the laser in where the eyepiece goes, so it bounces off of the secondary to the primary. If the primary is center marked, then all you have to do is match up your laser dot to the marked dot and you're collimated!

The optical tube assembly on the TPO Imaging Newtonian telescope is made of rolled steel and painted white. The ends of the tube are die-cast aluminum, which contribute to the OTA's rigidity. Steel is a bit heavier than traditional aluminum, but since it has a lower coefficient of thermal expansion, your telescope will tend to hold its shape (and therefore, hold focus) as temperatures fluctuate throughout the night. The inside of the OTA is painted in a matte black finish, which stops stray light in its tracks.

A single speed Crayford-style focuser rounds out this package. There is also a little knob on the bottom of the focuser that controls the tension, so that you can make adjustments depending on the weight or distribution of your load. You will also receive a 1.25 inch compression ring adapter for use with 1.25 inch eyepieces.

The telescope comes with dual split-hinged mounting rings that are made of die-cast aluminum and felted on the inside to cradle the OTA without scratching. There are threaded holes on the underside of the rings that allow installation on either a Vixen-style (included) or Losmandy-style dovetail plate. The top of the rings is also drilled so that you can mount accessories.

All TPO Imaging Newtonians come with an 6x20 straight-through finderscope. The ocular has a non-illuminated crosshair and has 13mm of eye relief. A quick-release mounting bracket is also included.

TPO 6 inch f/6 Imaging Newtonian Highlights


  • 2 inch single-speed linear Crayford-style focuser with 1.25 inch adapter
  • 6X30 White Crosshair Finderscope with Bracket & Dovetail Shoe
  • Dual hinged rings with Vixen-style dovetail
  • Length: 23 inches


Aperture152 mm (5.98")
Camera/Eyepiece Connection2" Nosepiece
Dawes Limit0.76 arcseconds
Focal Length916 mm
Focal Ratiof/6
Free ShippingYes
Hightest Magnification304x
Light Gathering Power472x
Limiting Magnitude14.7
Optical DesignNewtonian
Secondary Obstruction45mm
Tube Diameter178mm
Tube Length840mm
Tube Weight14.3 lbs
Warranty2 Year Warranty

Customer Reviews

Based on 2 reviews Write a review


Ask a Question
  • What is the diameter of the secondary mirror/central obstruction? Thanks.

    Approximately 50mm

  • How long is the dovetail included wit5h the telescope? is it possible to add a second dovetail at the top of the mounting rings?

    The dovetail that comes with the scope is 6" long. Yes there are mounting holes in the top of mounting rings to mount a second dovetail bar.

  • What differentiates this 6" F6 imaging"newt from a standard 6" F6 "visual"reflector? Thx, Greg

    Generally speaking Imaging Newtonians have a larger secondary mirror and a faster focal ratio then a visual scope.

  • I like a clearance 6-inch f/5 Newtonian: it offers rich field to planetary views, but the lightly made rack and pinion focuser really needs an upgrade. This 6" f/6 looks like an affordable alternative. Will the TPO stock single speed Crayford focuser r

    If you are looking to add this much weight to the stock focuser, it would be worth looking int a replacement focuser from a different manufacturer. Please email us at or give a phone call at 1-800/483-6287.

  • Can you confirm that the focuser on this scope has sufficient inward travel to allow a Canon 1100D DSLR to come to focus?

    Yes, this focuser can reach focus with a DSLR. You actually need to add the included 35mm extension to allow a normal eyepiece to focus, and then you remove the extension for the camera.

  • I am currently using a series of Optec items such as IFW, TCFS, and Pyxis with a STF-8300M camera. Is it possible to reach back focus with all that equipment in place? What is the backfocus maximum? Thanks.

    No, there is no way that this stack will reach focus with this telescope. With the shortest possible Optec adapters, a TCFS at mid focus, a 2" Pyxis with nosepiece, and an IFW with scope side T adapter take up 171.5mm. Adding a camera adds an additional

  • Does this come with any eyepices, or do I buy them separately?

    This telescope does not come with any eyepieces, but it is capable of using both 2" and 1.25" eyepieces with included adapters.

  • How well does this telescope do for visual observing?

    This scope does work well for visual use. A reflector like this will do and excellent job for fainter objects and will have less chromatic aberrations than any refractor of similar size. For eyepieces with a wide field of view, I would recommend getting t