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Inv.
2585 V.10 Eyepiece lens 1640-1660 [attr.] Ippolito Francini or Evangelista Torricelli or Jacopo Mariani Glass, wood, cardboard Diameter 39 mm |
Description Biconcave eyepiece lens mounted in a wooden ring covered in cardboard. The diameter of the lens is 27 mm, the focal length is -84 mm (the negative focal length means that the lens is diverging). The glass, which has a slight green tint, contains elliptical bubbles. On one side of the ring all that remains legible is the written word "braccia", a unit of measure indicating the Florentine origin of the lens. The whole inscription is, however, preserved in an old catalogue: "Di braccia 5 ½". This eyepiece was therefore to be used with a telescope of 5 ½ braccia (corresponding to 3210 mm). The lens can be dated to between 1640 and 1660. |
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