Canon Patent: RF 300mm f/2.8 IS And RF 400mm f/2.8 IS

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And yet another Canon patent application: two telephoto fast primes for the RF mount.

Canon patent application 2023104022 (Japan, published 7/28/2023) discusses optical formulas for two fast telephoto prime lenses for the RF mount: RF 300mm f/2.8 IS and RF 400mm f/2.8 IS.

From the patent literature:

Optical System and Imaging Device Having the Same

Description of the Related Art

An optical system used in an imaging apparatus is required to be compact and lightweight as a whole, and to have high optical performance capable of satisfactorily correcting various aberrations including chromatic aberration. As a compact optical system, a so-called telephoto type optical system is known in which a lens group with positive refractive power is arranged on the object side and a lens group with negative refractive power is arranged on the image side. However, in the telephoto type optical system, the longer the focal length, the larger the entire system, and the use of a lens with a large diameter or a heavy lens tends to increase the weight of the entire optical system.

Example 1

  • Focal length: 294.99
  • F-value: 2.90
  • Half angle of view: 4.19
  • Image height: 21.64
  • Overall length: 280.25
  • Back focus: 37.47

Example 2

  • Focal length: 390.00
  • F-value: 2.90
  • Half angle of view: 3.18
  • Image height: 21.64
  • Overall length: 370.50
  • Back focus: 37.00

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Canon Patent: RF 15mm f/2 And RF 12mm f/2.8 Lenses

Canon Patent
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And here is another Canon patent application, for two RF mount lenses.

Canon patent application 023104029 (Japan, 7/28/2023) discusses optical formulas for two fast prime lenses for the RF mount: RF 15mm f/2 and RF 12mm f/2.8.

From the patent literature:

Optical System and Imaging Device Having the Same

A wide-angle lens is provided that is compact and lightweight, and provides a high optical performance in which fluctuations in aberration due to focusing are suppressed while a high photographing magnification can be obtained at the time of photographing at the shortest distance.

Description of the Related Art

In recent years, there has been a demand for wide-angle lenses used in imaging apparatuses that are compact as a whole and that are capable of obtaining a high photographing magnification at the time of photographing at the shortest distance. In addition, there is a demand for a lens having high optical performance in focusing from infinity to the closest object.

In a wide-angle lens, in order to obtain a high photographing magnification at the time of photographing at the shortest distance, it is necessary to increase the amount of movement of the focus lens group, which makes it difficult to reduce the size of the entire lens. In order to reduce the amount of movement of the focus lens group, it is necessary to increase the refractive power of the focus lens group.

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