The first telescopes used lenses, known as refracting telescopes ... focus with diffracting concentric ridges, but the color ...

Designers of refracting telescopes figured out ... thereby solving the color-fringe problem. Despite myriad embellishments, however, most optical telescopes in use in the 21st century derive ...

9.53 inch Clark Refractor The main telescope is the original 9.53 inch refractor built ... green, and blue filters for color images, and a wide assortment of new eyepieces. The Celestron telescopes ...

The original instrument to occupy the 25-foot diameter dome was the 10.5-inch Bausch refracting telescope (f/15.5) installed in the brand new observatory in 1953. Bausch & Lomb Company gave the ...