About Ritchey-Chretien Telescopes…
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.
10" f/8 Ritchey-Chretien Astrograph Highlights…
Optical Highlights: This Third Planet Optics (TPO) Ritchey Chretien telescope has 10" (250mm) of aperture and a focal length of 2000mm. The concave hyperbolic primary and convex hyperbolic secondary are made from low expansion quartz, and finished with a scratch-resistant highly reflective 99% 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 GSO Ritchey-Chretien works wonders at keeping stray light at bay. Inside the tube are multiple light baffles, and the primary and secondary mirrors are baffled as well.
Carbon Fiber Optical Tube: Besides being very high tech and impressive-looking, carbon fiber is light-weight, strong, and has a lower coefficient of expansion than aluminum. That means your OTA will be tough and not weigh more than it has to, but also that your focus won't tend to shift as temperatures change throughout the night.
Cooling Fans: The 10" Ritchey has three small cooling fans in the rear cell that help cool the inside of the tube down and bring it to ambient temperature so that you can start imaging sooner! The fans are powered by an external battery pack. This battery holder accepts 8-AA batteries (sold separately).
3.3" Dual Speed Fully-Rotatable Crayford Focuser You'll love the 3.3" 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. The 3.5" focuser graduates down to 2", and a 1.25" compression ring adapter is also included so you can use both 2" & 1.25" eyepieces. Three 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.
Two Dovetails & Finderscope Base Included Talk about versatility! A Losmandy-style dovetail is attached to the bottom and top of the OTA. The dovetail(s) 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.
- Additional Information
SKU OS-10RC-CF Manufacturer TPO Telescope Series TPO Ritchey-Chretien Optical Design Ritchey-Chretien Mount Type None - Optical Tube Only Warranty 2 Year Warranty Telescope Aperture 10" Telescope Focal Length 2000mm Telescope Focal Ratio f/8 Optical Tube Outer Diameter 11.75" at castings, 13.5" max (dovetail to dovetail) Length of Optical Tube 24.75", without focuser Optical Tube Weight 31 lb. without focuser, 33 lb. with focuser Optical Coatings 99% Dielectric Tube Color or Finish Carbon Fiber Limiting Stellar Magnitude 14.5 Highest Useful Magnification 300x Diagonal Included? No - Sold Separately Finder Included None OTA Mount Type Losmandy-Style Dovetail
- Included Items
- TPO 10" f/8 Ritchey-Chretien Carbon Fiber OTA
- (2) M117 X 25mm Spacers
- M117 X 50mm Spacer
- Top & Bottom Losmandy Dovetails
- TPO 3.3" Two Speed Crayford Focuser, Graduated to 2", with 1.25" Adapter
- Vixen Finder Shoe
- Battery Box for Fans (holds 8-AA batteries, not included)
- Dust Caps
- Questions & Answers
- Support / Downloads