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ASA - Astrograph 20" f/3.6 Open Truss

Model#: ASA20NG-OK3

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Availability: In stock


Manufactured by: ASA - Astrosysteme Austria


The N-Series Astrographs may be used for three different focal lengths, by using appropriately calculated correctors. The original focal length of the device is shortened by the 3" Wynne corrector, by a factor of 0.95, to f 3.6 . Given the matching corrector, the system can be shortened by a factor of 0.73 or extended by a factor of 1.8! As usual, in uncompromising quality! Hence, by buying the correctors, you get three telescope focal lengths with perfect picture quality united in one compact and lightweight telescope! With a few movements, the optic is adjusted in focal length and aperture ratio to the shooting situation! Example: An ASA Astrograph N 8"/f3.6 with 730 mm can also be used as 558mm f 2.75 or as 1380mm/ f 6.8 (see correctors).

As of now we produce the 16” and 20” Astrographs as Truss tubes optional. This design enables a rapid adaption to the ambient temperature and decrease tube seeing. Furthermore the stiffness of the system increases at such size of optics.

Additional Information

Name ASA - Astrograph 20" f/3.6 Open Truss
Manufacturer ASA - Astrosysteme Austria
Model ASA20NG-OK3
Aperture 500 mm
Focal Length 1900 mm
Focal Ratio f/3.6
Focuser ASA-OK3
Image circle 50 mm
Optical Design Newtonian Astrograph
Optical Tube CFK-Sandwich