Refracting telescope
Refractors were the earliest type of optical telescope. The first practical refracting telescopes appeared in the Netherlands about 1608, and were credited to three individuals, Hans Lippershey and Zacharias Janssen, spectacle-makers in Middelburg, and Jacob Metius of Alkmaar. Galileo Galilei, happening to be in Venice in about the month of May 1609, heard of the invention and constructed a version of his own. Galileo then communicated the details of his invention to the public, and presented the instrument itself to the Doge Leonardo Donato, sitting in full council.
Zacharias Janssen
Over the years there have been claims Zacharias Janssen invented the telescope and/or the microscope in Middelburg between 1590 and 1618. Zacharias worked for some period of his life as spectacle-maker (a very competitive and secretive trade) and at one time lived next door to Middelburg spectacle maker Hans Lippershey, also claimed to have invented the telescope. Janssen's attribution to these discoveries is debatable since there is no concrete evidence as to the actual inventor, and there are a whole series of confusing and conflicting claims from the testimony of his son and fellow countrymen.