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Canon Patent: 50mm f/4 IS Macro And 90mm f/4 IS Macro

Canon Patent

Canon patent application 2024010559 (Japan, published 01/24/2024) discusses optical formulas for two macro lenses for the RF mount:

  • 50mm f/4 IS Macro
  • 90mm f/4 IS Macro

From the patent literature:

  • An object of the present invention is to provide a compact and high-performance optical system in a macro lens, in which a focus lens group is made lighter and smaller, achieving higher focus stop precision and faster focusing speed.
  • BACKGROUND ART
    A macro lens is known as a lens capable of close-up photography. In recent years, there has been a demand for a macro lens that has high optical performance with little aberration variation in the entire focus region.
  • Patent Documents 1 and 2 disclose macro lenses that correct aberration fluctuations during focusing by moving a large focus lens group during focusing.
  • However, in the macro lenses described in Patent Documents 1 and 2, the actuator becomes large in order to move a large focus lens group, and the focus lens group becomes large, resulting in a decrease in focus stop accuracy and focus speed. There was a problem.
  • The present invention provides a compact and high-performance optical system in a macro lens by reducing the weight and size of the focus lens group, achieving high focus stop precision and high speed focusing speed.

Example 1

  • Focal length: 111.29
  • F value: 4.12
  • Half angle of view: 11.00
  • Image height: 21.64
  • Total length: 125.00
  • Back focus: 34.03
  • Magnification: 1.0

Example 2

  • Focal length: 90.00
  • F value: 4.12
  • Half angle of view: 13.52
  • Image height: 21.64
  • Total length: 120.00
  • Back focus: 21.58
  • Magnification: 1.0

Example 3

  • Focal length: 110.00
  • F value: 4.12
  • Half angle of view: 11.13
  • Image height: 21.64
  • Total length: 119.99
  • Back focus: 43.07
  • Magnification: 0.5

Example 4

  • Focal length: 52.00
  • F value: 4.12
  • Half angle of view: 22.59
  • Image height: 21.64
  • Total length: 115.00
  • Back focus: 24.18
  • Magnification: 1.0
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