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ASA AZ800 800mm f/6.85 Ritchey-Chretien Telescope System


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  • Please email OPT or give one of our OPT telescope experts a call at 800-483-6287 to order. This is a custom order and deposits are NON-REFUNDABLE.
  • All devices are mounted in Nasmyth focus at the center of gravity, eliminating the need to balance with different cameras and accessories
  • Achieves unprecedented positioning and tracking accuracy thanks to ASA's Direct Drive technology
  • For time frames or questions, please contact us at 800-483-6287.

Product Details

  • AZ800 is a 0.8m (800mm) fully automated observatory telescope system. This Ritchey-Chrétien Alt-Az telescope has Nasmyth focus, in which all experience of the designer, Dr. Philipp Keller are incorporated and combined with state-of-the-art CNC technology from ASA.


    The azimuthal design allows a very compact dimension for this telescope opening. The Nasmyth type focus is steered by a motor-rotated Tertiary mirror either through the left or right fork side and you can switch between these foci within a few seconds with a mouse click. For example, you can visually use one of the foci, the other photographically, without constantly having to rebuild. Likewise, it is of course conceivable to equip one side with a planetary camera, the other hand, with a reducer. Since all devices are mounted in Nasmyth focus at the center of gravity, this eliminates the need to balance with different cameras and accessories. For visual observation, this provides maximum comfort because the viewing height is always at the same height and the view is always horizontal.

    Direct Drive Technology

    The ASA AZ800 achieves unprecedented positioning and tracking accuracy thanks to ASA's Direct Drive technology, combined together with an encoder resolution on the telescope axis of better than 1/100 arc seconds. This is also a benefit of the azimuthal construction, which avoids the hysteresis effects caused by parallactically mounted telescopes and load changes. The optional ASA Derotator precisely corrects the field rotation that occurs with all azimuthally mounted telescopes during long exposures. Also with this focal length, seeing-limited shots are no problem even without autoguiding at shutter speeds of 5 minutes thanks to ASA's MLPT tracking system.


    The optics of the AZ800 are uncompromised. It features quartz glass optics made in-house by ASA (L / 8 Wavefront Peak to Valley), making ASA one of the few manufacturers who can achieve the surface quality required for outstanding imaging performance in large diameter RC and Nasmyth systems.

    The AZ800's optical design uses the RC system (including optional correctors). Due to two aspherical optics, these systems are more complicated to produce than, for example, a Dall Kirkham system, which leaves one of the two mirrors spherical, resulting in large aberrations. For us, this optical compromise is out of the question. Normally large RC telescopes with large central obstructions do not make good planetary imaging telescopes due to low contrast. This is not true of the AZ800!

    Main Features

    • Optical Design: Ritchey-Chretien
    • Focal Ratio System: f/6.85
    • Focal Length: 5480mm
    • Focus: Nasmyth
    • Linear Central Obstruction: 41%
    • Back focus: 263mm
    • Field of view: 120mm (without flattener)

    Mechanical Structure

    • Tube Design: Aluminium main mirror and secondary mirror cell, connected with carbon tubes
    • Tube swing radius: R1350mm
    • Material: High-end aluminum and carbon fiber truss
    • Weight: 800kg

    Primary Mirror

    • Optical diameter: >/= 800mm
    • Focal ratio: f/2.5
    • Mirror mounting: 18-point floating cell
    • Strehl >/= 94%
    • Mirror substrate: Fused silica, ultra-low thermal expannsion 0.55e-6/K
    • Mirror coating: All mirror substrates are made from fused silica, ultra-low thermal expansion 0.55e-6/K

    This ASA AZ800 800mm f/6.85 Ritchey-Chretien Telescope System 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.

    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.

  • specifications

    Aperture800mm (31.5")
    Back Focus263 mm
    Dawes Limit0.15 arcseconds
    Focal Length5480mm
    Focal Ratiof/6.9
    Highest Magnification1600x
    Light Gathering Power13061x
    Optical DesignRitchey Chretien
    Tube Weight1763.7 lb
  • included items

    • ASA AZ800 800mm f/6.85 Ritchey-Chretien Telescope
    • Motorized main mirror cover
    • ADR6 ASA De-Rotator with absolute encoder (inner diameter: 160mm; Load capacity: 15kg)
    • 4 Zoll Ritchey-Chrétien Field Flattener
    • 4 Zoll Ritchey-Chretien Reducer
    • 5 Zoll Ritchey-Chretien Reducer
    • Client-specific camera adapter
    • Mirror substrate from Zerodur (extra charge)
    • Different mirror coating (extra charge)
    • Filter wheel
    • 3. + 4. Nasmythport

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