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RE: Off Axis Optics

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Posted by Robert May on May 1, 2000 23:31:52 UTC

There are a number of different optics configurations for doing off axis optics. Simple stuff is to use a small mirror (one that stays within the Raleigh Criteria for accuracy of the surface) of, lets say 6" and have a F/ratio of about 15 and you will be able to do a Herschelian scope (Newtonian without the centered secondary mirror) and reflect the light back wherever you want it to be. Then there`s the Stevick-Paul design which allows for the light to be completely unobstructed again. That one calls for 4 mirrors, first is parabola, second is convex spherical third is concave spherical of the same radius as 2 and fourth is a flat. There is also a configuration where the third and fourth swap thier surface configurations but haven`t looked into it too much. All are on the web.
If this gets through, I am most assuredly done with the ACCESS1 as my ISP!

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