# Newton Astrographs

The Newton Series Astrographs have a focal ration of f/3.8. Given the matching corrector the system can be shortened or be extended with a few movements.

The original focal length of the device is shortened by the 3" Wynne Corrector (Standard with Newton Series Astrographs), by a factor of 0.95, to a focal ratio of 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! With the 2" or the 3" Reducer a focal ratio of f/2.75 results while with the Barlow Flat Corrector the focal ratio will be f/6.8. 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: A Newton Series Astrograph 8" with 730mm (f/3.6) can also be used as 558mm (f/2.75) or as 1380mm (f/6.8) – look for details in our correctors info.

All Astrographs have optics of Suprax material with Zygno interferogram with P/V <1/7 lambda wave, 97% reflection. All flat mirrors offer the same specs. On request we offer premium Sital mirrors by LOMO in configuration with our Astrographs. (longer delivery times).

The focuser of our Astrographs have been beloaded with 8kg for successful tests. To attain the weight of 8kg additional weights have to been added, because no camera system available on the market has such a heavy weight.

Basically the essential expose times with the fast Astrographs are at most in the range of 600 seconds for a sub frame. For external Guiding (Guidescope) one has to be attend that the focal length of the Guidescope is in a range of at least of the half of the focal length of the used Astrograph. In exceptional cases if one like to take expose times longer as 600 seconds for an image and in case if no internal guide chip is available, we would recommend an Off-Axis-System for guiding.

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.

### Overview:

Name | Aperture | Focal lenth | Secondary | Focuser | Corrector | Image Circle |
---|---|---|---|---|---|---|

ASA8N-OK3 f/3.6 | 200mm | 720mm | 90mm | ASA-OK3 | 3KORRW | 50mm |

ASA10N-OK3 f/3.6 | 250mm | 900mm | 100mm | |||

ASA12N-OK3 f/3.6 | 300mm | 1080mm | 120mm | |||

ASA16N-OK3 f/3.6 | 400mm | 1440mm | 130mm | ASA OK3Z | ||

ASA20N-OK3 f/3.6 | 500mm | 1900mm | 150mm |