Used ASA 10" F/3.6 10N Astrograph OTA - Sold
This ASA 10" F/3.6 model-10N Astrograph Optical Tube Assembly (OTA) is the perfect starting point for the serious astronomer who wishes to configure a custom system for doing astrophotography. The OTA is the basis of a fast, wide-field imaging telescope system, which will provide the highest quality imagery and be capable of working at multiple focal lengths. This astrograph OTA has an aperture of 10", a focal length of 950mm, a natural focal ratio of f/3.6, a tube length of 790mm, a tube diameter of 300mm, a Newtonian output port compatible with 3" focusers, and weighs in at only 24.25lbs (11kg).
This 10" F/3.6 model-10N Astrograph OTA by ASA will accept the 3" model A2-OK3Z electronic motorized focuser by ASA.
This ASA astrograph tube assembly is manufactured of sandwiched carbon fiber. Carbon fiber technology adds to the astrograph's visual appeal, while making it approx. 60% lighter. Thanks to the thermal stability of carbon fiber, your focus remains stable over a long period of time. The tube assembly's stability means the optics remain collimated longer. Speaking of collimation, the primary mirror of the ASA 10N Astrograph includes a center triangle reference mark for ease of collimation. The internal surface of each tube assembly is also treated with black velvet, to reduce scattered light.
ASA astrographs all have a fast optical system (small f/#). You can achieve good signal-to-noise ratio with your CCD using short exposure times. The N-series astrographs all have a natural focal ratio of f/3.8. Their system f/# can be reduced or extended easily by the user, so the natural focal length of the device can be shortened by a factor of 0.75x or increased by a factor of 1.8x, while retaining the highest-quality imagery. You can enjoy all three telescope focal lengths, simply by using each of the three appropriate corrector lenses.
For example, by installing the 3" Wynne Corrector lens (standard with N-models) you achieve a focal ratio of f/3.6. With the 2" (or 3") Reducer, a focal ratio of f/2.75 results. Using the ASA Barlow Flattener Corrector, the focal ratio will be f/6.8. The field corrector lenses will handle the largest CCD arrays currently popular, because all of the ASA correctors provide sufficient backfocus (flange focal distance).
ASA astrographs are sold in two different models: The N-series use a parabolic primary mirror, while the H-series use a hyperbolic primary. This product uses a parabolic primary mirror. ASA primary mirrors are all verified to meet stringent specs by interferometric testing, prior to their assembly into a telescope! Testing has shown they produce the finest spot sizes available in currently-available fast telescopes.
Their uncompromising optical design by Philipp Keller, Dipl. Physics, (Germany), and use of the finest materials available, yields imaging performance covering a large field of view, a fast f/#, ultra-stable construction, yet they are light weight. The new "double thin spider", now supplied with the ASA N-Series astrographs, is rigid while significantly reducing diffraction spikes from bright stars, normally caused by the spider! ASA's astrograph product line is an astrophotographer's dream come true!
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