Takahashi Refractors

Takahashi refracting telescopes — fluorite and ED apochromats from 60 mm to 150 mm. The FC and FS doublets use a fluorite crystal element for colour correction in two elements; the TOA and TSA triplets and the FSQ Petzval astrographs add elements for flatter fields and wider corrected circles. Every tube pairs with a published flattener, reducer or extender, and a system chart that names the exact spacing.