Afocal zooming optical system
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorHiroyuki Kato
Life of this patent
Estimating the term…
Abstract
An afocal zooming optical system includes, in order from the object side, an objective optical unit comprising a positive first lens group, an erecting prism component and a negative second lens group, and an eyepiece optical unit comprising a three-element positive third lens group and a single-element positive fourth lens group, which system performs zooming by moving the second and third lens groups in different directions along the optical axis and satisfies certain conditions.
Claims4
An afocal zooming optical system comprising, in order from the object side, an objective optical unit comprising a positive first lens component, an erecting prism component and a negative second lens component, and an eyepiece optical unit comprising a three-element positive third lens component and a single-element positive fourth lens component, which system performs zooming by moving said second and third lens components in different directions along the optical axis and satisfies the following conditions:
- few/fet.ltoreq.1.30
- 1.70<fG4/fG3<4.50
- where few is the focal length of the eyepiece optical unit at low magnification, fet is the focal length of the eyepiece optical unit at high magnification, fG3 is the focal length of the third lens component, and fG4 is the focal length of the fourth lens component.
Dependencies are inferred from the claim text.