TPO 6" f/9 Ritchey-Chretien Steel Astrograph w/ Advanced VX Mount & Polar Finder

  • Sale
  • $1,147.50
  • Regular price $1,350.00
  • TPO 6" f/9 Ritchey-Chretien Steel Astrograph w/ Advanced VX Mount & Polar Finder

    • Sale
    • $1,147.50
    • Regular price $1,350.00
    • ITEM #



    • Only $40.00 Gets you Lifetime Warranty!
    • Aperture: 6 inches 
    • Focal Length: 1370mm
    • Focal Ratio: f/9

    TPO 6" f/9 Ritchey-Chretien Steel Astrograph w/ Advanced VX Mount & Polar Finder

    In 1910, American optician & astronomer George Willis Ritchey & French astronomer Henri Chretien designed a specialized Cassegrain that would later become the telescope of choice for many observatories and professionals around the world. The Ritchey-Chretien astrograph has many benefits that make this design appealing to anyone who is serious about astro-photography or imaging. Here are a few of those benefits:

    • Good-bye Coma: An RC has virtually no coma (stars look like little comets around the edges of the field), which means there will be greater image quality across a wider field of view.
    • No Chromatic Aberration: Because a Ritchey-Chretien does not use lenses or corrector plates, the design does not suffer from chromatic aberrations, or false color. If you've ever looked through an achromatic refractor (non-APO), you will have seen chromatic aberration.
    • No Spherical Aberration: The use of hyperbolic mirrors for both the primary and secondary removes the problem of spherical aberration from this optical system, an optical effect caused when light rays do not all come to focus at the same point, resulting in an image that is not in perfect focus.


    6 inch f/9 Ritchey-Chretien Astrograph Highlights


    Optical Highlights: This Third Planet Optics (TPO) Ritchey Chretien telescope has 6 inches (152mm) of aperture and a focal length of 1370mm. The concave hyperbolic primary and convex hyperbolic secondary are made from a highly uniform BK7 glass blank, and finished with a scratch-resistant highly reflective dielectric coating for great contrast. The primary mirror is fixed in place in a metal mirror cell, and the secondary resides in a metal housing that can be collimated.

    Multiple Knife-Edge Baffle System: The computer designed and optimized baffle system in the TPO Ritchey-Chretien works wonders at keeping stray light at bay. Inside the tube are eight light baffles, and the primary and secondary mirrors are baffled as well.

    2 inch Dual Speed Crayford Focuser You'll love the 2 inch 1:10 Dual Speed Crayford focuser that comes standard on this RC. The dual knobs allow you choose the speed with which you focus. One turn of the larger knob equals ten turns of the smaller knob, so minute adjustments when you are "almost there" are easy to do with this high quality focuser. A 1.25 inch compression ring adapter is also included so you can use both 2 inch & 1.25 inch eyepieces. Two spacers are included as well, which allows you to adjust the focus position for different cameras with various back focus requirements.

    A Fixed Primary Eliminates Image Shift Schmidt-Cassegrain & Mak-Cassegrain telescopes achieve focus by moving the primary mirror back and forth inside the optical tube assembly, and this movement can cause image shift. While manufacturers have done a pretty good job of minimizing image shift on their telescopes, a moveable mirror makes it almost impossible to eliminate it completely. The Ritchey-Chretien has a primary that is fixed in place, removing the possibility of image shift and also the job of collimating the primary.

    Vixen-Style Dovetail Rail & Finderscope Base Included A full length Vixen-style dovetail rail is attached to the TPO Ritchey-Chretien optical tube assembly for quick and easy attachment to a Vixen-style mount. The rail can be removed if you wish to use mounting rings (sold separately) instead. While a finderscope is not included, the OTA comes standard with a finderscope base that will accept Vixen-style brackets (if you want an optical finder) or most red dot finders.

    TPO Product Number: BLK-6RC

    Additional Information

    Aperture152 mm (6")
    Focal Length1370mm
    Focal Ratiof/9
    Free ShippingYes
    Highest Useful Magnification300x
    Limiting Stellar Magnitude13.6
    Mount TypeEquatorial Go To
    Optical DesignRitchey Chretien
    OTA Mount TypeStyle Dovetail
    Warranty2 Year Warranty

    Questions & Answers

    Ask a Question
    • I've read that rc tunes are not good for regular observing would I need to purchase a 2nd Ota and will I this kit require a autoguiderO Aa

      Hello Mike, Thank you for your question. It really depends on what you are looking to do with the telescope. If you are looking to use this telescope for visual observation, it might be better to get an SCT or Newtonian optical tube because of their smal

    • I noticed this includes the Advanced VX mount and I am curious if you are modifying the counterweight as the OTA weighs 12.3 and the weight is 12? I have the Advanced VX mount and was considering just purchasing the OTA.

      No modification of the weight should be needed - the weight will just need to be moved up or down the counterweight shaft until you find the balance point with the RA lock disengaged. The farther from center down the shaft, the more weight the counterweig

    • I'm trying to use an Orion 80 short tube as guider. I need 2 rings (100 to 108 mm OD ?), dovetail plate (for 6" RC) and 2 dovatail adapters. Can you tell me a correct combination ?

      ADM now offers an AA-VRC6 dovetail rail, and then you can use a LO-DVR108 or AA-VR125 (ADM only makes 100mm and 125mm, and the 100mm is too small). This combo would let you mount your guidescope.

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