Welcome

Quick picks ::: Cardiff University half-metre telescope

A short (but relevant) history of the refracting telescope
Conventional wisdom states that the refracting telescope is fast approaching four centuries old, but it may have been invented by the English mathematician Leonard Digges around 1550. Telescopes employing lenses appeared in the Netherlands during the first decade of the 17th century and the first attempt to patent such an instrument was made in 1608 by a German-Dutch lensmaker, Hans Lippershey (right).

English mathematician Thomas Harriot observed the Moon telescopically in 1609, but the greatest populariser of the early refractor was undoubtedly the famous Italian physicist Galileo Galilei (left) who widely published his observations of the Moon, Jupiter and its four main moons in a book entitled "The Starry Messenger". Another sixty years would elapse before Sir Isaac Newton's reflecting telescope appeared on the scene, by which time refractors of prodigious length had appeared to help overcome the false prismatic colours seen around bright objects with such simple lenses.

In 1729, Chester Moor Hall discovered a way of combining two lenses of differing optical properties that largely eliminated the chromatic aberration and permitted refractors of manageable length. Some thirty years later, John Dollond (right) and his son Peter further improved the performance of the achromatic refractor by adding a third lens to the objective. To this day, these so-called triplets are highly sought after by refractor aficionados for their superb colour correction and suppression of other image-degrading optical aberrations.

The present day: a new kid on the block
The use of exotic modern glass and aspheric optical surfaces has given rise to true apochromats, able to meet the critical demands of just about any visual and astroimaging application. The contemporary research-grade refractor is therefore a specialised and highly sought after instrument, but one that has been prohibitively expensive in large apertures — until now.

Using his specialist optical knowledge gained during more than twenty years of commercial optical engineering, English optician Peter Wise, in collaboration with John Wall, firmly believe that they have created the next evolutionary step in refractor development, to be known as the Wall-Wise Zerochromat. Using a folded optical design and a patented corrector lens assembly, the Zerochromat delivers diffraction-limited, unobstructed large aperture performance in a compact and lightweight carbon-fibre tube assembly.

For more information on this exciting new instrument, please inspect our Products page.