Albada finder
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorAkihiro Arai
Life of this patent
Estimating the term…
Abstract
An Albada finder has a negative objective lens and a positive eyepiece lens. A frame is formed inside the area of the object-side surface of the positive eyepiece lens and a partial reflection area is formed on the eyepiece-side surface of the negative objective lens. The partial reflection area reflects an image of the frame. The frame is formed to enclose a small area of the object-side surface of the eyepiece lens while the partial reflection area is formed to enclose a small area of the eyepiece-side surface of the objective lens. Substantially all of the remaining area of the eyepiece-side surface of the negative objective lens not enclosed by the partial reflection area fully transmits all light incident on the surface.
Claims19
An Albada finder having a negative objective lens and a positive eyepiece lens, said Albada finder comprising:
- a frame formed inside an area of an object-side surface of said positive eyepiece lens;
- and
- a partial reflection area formed on an eyepiece-side surface of said negative objective lens, said partial reflection area reflecting an image of said frame,
- wherein said frame is formed to enclose a small area of said object-side surface of said eyepiece lens,
- wherein said partial reflection area is formed to enclose a small area of said eyepiece-side surface of said objective lens, and
- wherein substantially all of a remaining area of said eyepiece-side surface of said negative objective lens not enclosed by said partial reflection area fully transmits all light incident thereon.
An Albada finder having a negative objective lens, a positive eyepiece lens, an image boundary frame formed on an object-side surface of said eyepiece lens, and a total reflection area formed on an eyepiece-side surface of said objective lens for reflecting an image of said image boundary frame back to said eyepiece, said Albada finder further comprising:
- a focusing frame formed inside an area of said object-side surface of said positive eyepiece lens enclosed by said image boundary frame;
- and
- a partial reflection area formed inside an area of said eyepiece-side surface of said negative objective lens enclosed by said total reflection area, said partial reflection area reflecting an image of said focusing frame,
- wherein an area of said eyepiece-side surface of said negative objective lens between said total reflection area and said partial reflection area, fully transmits all light incident thereon.
Dependencies are inferred from the claim text.