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

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