A phoropter is an instrument comprised of cylinders, prisms, and lenses that measures the eye’s refractive error to help determine and eye prescription. Phoroptors ...

One of the most competitive segments in the amateur telescope marketplace these days spans 3- to 5-inch apochromatic ...

The triplet objectives are made with the same glass (both FCD 100 and FK-61) used in expensive refractors and are fully multicoated. The prisms are huge, allowing full coverage from any 1¼ ...