ASA 600 Ritchey Chretien Refracting Telescope

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ASA 600 Ritchey Chretien Refracting Telescope

This product by ASA is a Ritchey Chretien Telescope optical tube assembly (OTA), which is suitable for serious research or astrophotography. The ASA 600 mm f/7 Ritchey Chretien Telescope is a relatively fast (f/7) high quality optical system. The image is formed behind the primary mirror cell, using a perforated hyperbolic primary mirror and focusing is accomplished by moving the hyperbolic secondary mirror along its axis by a computerized electrical drive system. This Ritchey Chretien scope is similar in functionality to a Cassegrain, except that the field correction in the absence of a field-flattener lens is slightly better than a classical Cassegrain scope would provide.

The ASA 600 mm (~24-inch) aperture Ritchey Chretien Telescope is constructed using a combination of high-grade aluminum components and high strength carbon fiber materials in the form of an open truss tube assembly. 

ASA message: We at ASA produce our optics for all our telescopes since 3 years in our own optic shop, that is the only way to guarantee the highest optical quality for our ASA products.

The telescope was designed by Philipp Keller, a German physicist and optical engineer. This scope is suitable for use in remote, automated observing programs, in research applications where high quality imagery is mandatory, or for the most serious astrophotographer.

The ASA 600 mm Ritchey Chretien (R-C) Telescope has an aperture of 600 mm (23.62-inch) or approx. 24-inch, for a focal length of 4200 mm. It has a field of view of 57 arcminutes. This R-C scope will need a corrector lens when it is used with a large format CCD camera. In combination with a focal reducer or a field flattener, also designed by Philipp Keller, the scope can be used with a CCD detector with a diagonal size of 70 mm and still produce pin-point stellar images out to the corners. Because your ASA R-C Telescope is designed and manufactured to perform at the diffraction limit, your imaging results will only be limited by the prevailing seeing conditions at your site during image capture and your CCD camera equipment.


Some Specifications for the 600 mm Ritchey Chretien Telescope by ASA:


  • Aperture: 600 mm (23.62-inch)
  • Focal Length: 4200 mm
  • Focal Ratio: f/7
  • Back Focus: 360 mm (recommended)
  • FOV: 70 arcmin
  • Primary Mirror Performance: (Hyperbolic) - 1/8 wave P/V wavefront accuracy focused, 632 nm
  • Primary Mirror Cell Support: 9-point-floating
  • Mirror Set Materials: AstroSitall (LOMO)
  • Mirror Set Coatings: Al + SiO2 with 91% reflectivity
  • Telescope Tube: Combination - aluminum and sandwiched carbon fiber
  • Weight: 211.64-pounds (96 kg)

This ASA 600 mm f/7 Ritchey Chretien Telescope is a special order item and requires a 20% deposit when you place your order, and the balance will be required before the telescope leaves Austria. This deposit is fully refundable as long as you cancel your order before the telescope is imported. Please email OPT or give one of our OPT telescope experts a call at 1-800-483-6287, if you have any questions about this product.

Customer Note: The images represent generic ASA R-C telescopes for illustration purposes. Your telescope might look somewhat different.

Caution: Due to the size and weight of this telescope, it is strongly suggested that a customer have appropriate rigging gear, handling equipment, and personnel to assist, at hand when attempting to raise and attach this telescope to any mount! Use appropriate caution for personnel and equipment safety.


Aperture600 mm (23.5")
Back Focus360mm
Dawes Limit3 arcseconds
Focal Length4200 mm
Focal Ratiof/7
Glass TypeAstroSitall
Limiting Magnitude17.6
Optical DesignRitchey Chretien
Tube Weight211.36 lbs