History of the telescope received the report in November, and the English mathematician and astronomer Thomas Harriot, who used a six-powered telescope by the summer of 1609 to observe features on the moon. The Italian polymath Galileo Galilei was in Venice in June 1609 and there heard of the "Dutch perspective glass" by means of which distant objects appeared nearer and larger. Galileo states that he solved the problem of the construction of a telescope the first night after his return to Padua from Venice and made his first telescope the next day by fitting a convex lens in one extremity of a leaden
Optical telescope the specifications of the telescope, however they alter the way the telescopes properties function, typically magnification, apparent field of view and FOV. The smallest resolvable surface area of an object, as seen through an optical telescope, is the limited physical area that can be resolved. It is analogous to angular resolution, but differs in definition: instead of separation ability between point-light sources it refers to the physical area that can be resolved. A familiar way to express the characteristic is the resolvable ability of features such as Moon craters or Sun spots. Expression using the formula is given by the