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.
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|Name||ASA - Astrograph 20" f/3.6 Open Truss|
|Manufacturer||ASA - Astrosysteme Austria|
|Focal Length||1900 mm|
|Image circle||50 mm|
|Optical Design||Newtonian Astrograph|