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AG Optical - 20" Dall Kirkham Astrograph Telescope


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Availability: This item is special order. Delivery times will vary. Place your order today and your card will not be charged until the item ships.


This item is special order. Delivery times will vary. Place your order today and your card will not be charged until the item ships.

Manufactured by: AG Optical Systems


20" AG Optical Astrograph


  • Optics figured and quality tested as a system
  • Fast F6.7 system designed and baffled to cover 16803 size chip
  • 6" to 8.5" of back focus to support almost any combination of imaging components (dependent upon focuser selected)
  • Excellent coma free, astigmatism free, flat field performance over 70 mm image circle
  • Highly robust, precise Optec TCF-S3i focuser is standard.  Optional FLI Atlas focuser.
  • Outstanding field illumination across big chip cameras.
  • Carbon fiber truss tube engineered to provide rigidity and thermal stability.  Optional AGO Thermal Control System to automatically control fans, primary heater, and secondary heater.
  • Multiple spacer and camera adapter options


The 20" AG Optical astrograph has a medium focal ratio of f/6.7. This optical tube has a two element <0.5% reflective corrector which makes this possible by reducing many of the common light distortions such as coma.

This AG Optical astrograph is equipped with the Optec TCF-S3i focuser. This focuser is beneficial not only because it is electronic and mechanical, it also allows focuser memory and very flexible backfocus of 6" which is perfect or many astrophotography combinations. If you want even more, there are many spacers and adapters available you can shoose from.


20" Optical Tube


  • AG Optical has equipped this astrograph with a carbon fiber tube, which is praised for its lightweight and thermal stability.



  • Cleaning and maintaining a telescope is standard. Dust, particles and moisture can infiltrate inside so it is important to clean your optics and instrument once and a while. With precise computer precision, AG Optical has designed their astrograph to be completely disassembled and reassembled without worrying about spacing differences between the internal optics. The aluminum components are also computer machined precisioned.


  • There are three 12 voltage speed variant fans behind the mirror that regulates temperature stability.







Additional Information

Name AG Optical - 20" Dall Kirkham Astrograph Telescope
Manufacturer AG Optical Systems
Model 20IDK
Manufacturer Part No 20IDK
Telescope Aperture 16.1" and Up
Aperture 20"
Backfocus Distance 7.5" with Optec Gemini
Baffling primary and secondary baffles, baffled for 2" diagonal size chip
Dovetail Compatibility Heavy-duty, Losmandy "D" compatible dovetail plate included
Fans 3 x 80 mm fans
Focal Length 134"
Focal Ratio 6.7
Focuser Optec Gemini rotating focuser
Optical Tube CF Truss
Optical Tube Length 47"
Optical Tube Weight approx. 141 lbs
Secondary Mirror Obstruction 9"