The idea of combining the advantages of Cassegrain and Newtonian configurations in one instrument has been around for a long time but with very few examples commercially available.

Thus it was not so much a novelty of telescope optics , but rather the result of a long held need for the ideal all-round telescope for the amateur use that gave birth to the Takahashi CN-212.

The optical principle of the CN-212 is simple yet clever. From a primary short focus parabolic mirror, pierced centrally, different optical configurations are possible depending on the secondary mirror placed in the light cone. Here we have two telescopes in one, an f/12.4 Cassegrain as the basic configuration, with a hyperbolic secondary mirror for high resolution work, or when you require, by simply replacing the secondary mirror and coupled with a low profile 2" eyepeice adaptor and associated field corrector, you transform your instrument into a brilliant wide field Newtonian with a focal ratio of f/3.9