GALILEO 1.5x Erecting Eyepiece Lens, 1.25" Diameter For Sale

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GALILEO 1.5x Erecting Eyepiece Lens, 1.25" Diameter:
$25

GALILEO 1.5x Erecting Eyepiece Lens. PLEASE NOTE: THE DIAMETER IS 0.965" not 1.25" Galileo erecting lenses extend the reflector telescope's abilities. True astronomical telescopes will produce an upside down image. No erecting lenses, mirrors, or prisms are added. Having these elements in the telescope can cause images to be dim and or distorted. This fact makes terrestrial viewing (land viewing) difficult. The Galileo 1.5x Erecting Lens will turn the image in your telescope right side up to enable easy, comfortable terrestrial viewing.

Enhance your observatory capabilities with Galileo 1.5x erecting lens
Galileo lens turns image in your telescope right side up to enable easy, comfortable terrestrial viewing
Lens eliminates dimness and distortion
Model number OSER1

Dimensions: 4" x 1" x 1" Warranty: 1 year Limited Manufacturer
Materials: plastic and glass
Model No: Galileo OSER1

The Galilean telescope furnishes erect images, but has an extremely narrow field of view, which rapidly diminishes with increasing magnification. If, in fact, the field of view of a Galilean telescope with twenty magnifications is indicatively 15 minutes, that is, about half the apparent diameter of the Moon, it decreases to the order of only 5 minutes in a telescope with fifty magnifications. Such limited fields not only made the Galilean telescope unfeasible for civil and military purposes, but above all prevented, in the astronomical field, increments in performance over a few tenths of a magnification.

Johann Kepler (1571-1630) the German astronomer famous for his three laws on planetary motion , had however demonstrated, since 1611, the possibility of replaced the diverging eyepiece of the Galilean telescope with a converging lens, with the ensuing advantage of a much vaster and more highly contrasted field of view. But this optical combination, known today as the Keplerian (or astronomical) telescope, furnished upside-down images that made it unsuitable for terrestrial use. Galileo (1564-1642) was to remain always faithful to the optical combination that bears his name. However, in the 1630s, the Keplerian telescope began to be widely used, mainly due to the work of the Neapolitan optician Francesco Fontana (c. 1580-1656)

to the point of entirely superseding the Galilean one toward the middle of the century. The last great astronomical achievement

Johannes Hevelius, Selenographia

made with a telescope of this type, published by Hevelius (1611-1687) in 1647, was the representation of the lunar surface Moreover, the Keplerian telescope soon predominated for terrestrial purposes as well, thanks to the introduction of the so-called erector, an optical device, usually consisting of two convex lenses with the same focal length, which turned the image produced by the objective upright.

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