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ASA800 Ritchey Chrétien 800mm F6.85 Telescope System with DDM500

can be shipped within 180 days

Price includes VAT, plus delivery

The ASA800 combined with the ASA DDM500 Mounting offers outstanding performance for all types of research.

ASA800 Telescope

This version of the ASA800 RC features traditional Cassegrain focus. Its fast F2.5 primary mirror allows for a much more compact design and reduces the central obstruction to 41%. This therefore allows the ASA800 to provide much high contrast compared to traditional RC designs.

Included as standard with the ASA800 is secondary mirror focusing and motorised primary mirror covers. Available as an option is motorised collimation adjustment of the primary mirror. In normal use no drift of collimation should be expected. In the event that the telescope is installed in a very remote location with extended service intervals, then this option may be worth considering.

Available for the ASA800 are a matched 4" RC Flattener offering a 70mm corrected field, and a matched 4" RC Reducer with 0.64x reduction and 52mm corrected field.

Basic Telescope Specifications

Type Ritchey-Chretien
Aperture 800mm / F2.5
Focal Length 5480mm
Focal Ratio F6.85
Obstruction 41%
Image Field 120mm
Mirror Material Fused Silica
OTA Weight 246kg
Back Focus 346mm from rear flange


The DDM500 represents the pinnacle of ASA Direct Drive mounts. With a huge payload capacity of 500kg, the DDM500 allows for additional telescopeses to be to be mounted in addition to the ASA800. Infact the DDM500 is the highest capacity standalone Direct Drive mount fitted with absolute encoders available worldwide.

Loading of the DDM500 can actually be 2 x 500kg is twin scope configuration. You could therefore add a second ASA800 easily.

The DDM500 is designed to be used with a custom built Equatorial Pier. This is made for the latitude of the telescopes location. An EQ pier allows for the telescope to run without the need for a meridian flip. This is reliant on the mount being used within an observatory dome. Use within a ROR observatory does not permit this operation as the mount will not know the are walls to contend with! Unfortunately as good as the ASA800+DDM500 package is, we have not yet reached the stage where we can see through a wall!

The cost for the DDM500 Pier is provided on request and is dependent on latitude.

Basic Mount Specifications

Type EQ / Alt-Az (with add on)
Dual Mounting? Yes (2 x 500kg)
Motor ASA Direct Drive
Latitude Range 0-90 Degrees
Max Load 500kg (Single Telescope)
Mount Weight 281kg excl Counterweight
Slew Speed Up to 50° Second
Pointing (20°-85°) <8" RMS with Model and ASA telescope
Tracking (20°-85°) <0.25" RMS within 5min / over 5min 0.05" RMS/min
Control Software ASA Control One (Integrated Telescope, Mount, Observatory), Ascom and Custom options

Lead time on request

Typically this is 6-12 months depending on time of order. The production schedule is confirmed following deposit. The payment terms are 40% with order and 60% when the system is ready for shipping.


Please note the price of the telescope system is a guide. It is subject to exchange rate fluctuation. Due to the extended lead time, we fix the price in Euro and convert balances to GBP so that pricing follows the Euro. The price shown includes VAT at the current rate. All installations outside of the UK will be charged ex VAT. Local import taxes and VAT may then be chargeable for the country of import depending on the telescope application and local arrangements for academic use.

Delivery and Installation cost is not included

This telescopes requires professional installation. The nature of this telescope will require specialist shipping to its final destination. On site, a crane is required.

Astrograph Ltd offer professional installation services and can offer advice in this respect. Please contact us for details.

Browse these categories as well: Ritchey Chretien Astrographs, ASA