Canon Patent: RF 18-35mm f/1.8 DS & RF 120-300mm f/2.8 DS (Defocus Smoothing)

Defocus Smoothing
View Post

And here is another Canon patent application for two RF-mount lenses with Defocus Smoothing technology.

Canon patent application 2022175307 (Japan, published 11/25/2022) discusses optical formulas for two RF-mount lenses with Defocus Smoothing technology, RF 18-35mm f/1.8 DS & RF 120-300mm f/2.8 DS. No surprise Canon is porting this technology to the RF-mount. From the patent literature:

To provide a variable power optical system that obtains a good apodization effect over the entire zoom range and that has a small change in T number with variable power.

Description of the Related Art

Conventionally, in order to obtain an appropriate blurred image, there has been known an optical system equipped with a filter whose transmittance distribution changes, such as an apodization filter whose transmittance decreases as the distance from the optical axis increases. ing. Patent Literature 1 discloses an optical system in which apodization filters are arranged before and after the aperture of a single-focus lens.

However, since the optical system disclosed in Patent Document 1 is a single focus optical system, it is insufficient as a method for obtaining a sufficient apodization effect in each zoom state of the variable magnification optical system. In addition, as a specific requirement of a variable-magnification optical system, it is required that the change in brightness, that is, the T-number, is small when the magnification is varied, especially in video shooting.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a variable magnification optical system and an optical apparatus which have a good apodization effect over the entire zoom range and have a small change in T-number due to variable magnification.

Example 1

  • Focal length: 18.60-33.78
  • F-value: 1.80-1.86
  • Half angle of view: 37.69-23.05
  • Image height: 14.37
  • Overall length: 168.50
  • Back focus: 38.56-39.91

Example 2

  • Focal length: 18.50-34.00
  • F-value: 1.75-1.86
  • Half angle of view: 37.99-23.03
  • Image height: 14.45
  • Total length: 163.25-166.00
  • Back focus: 38.56-41.75

Example 3

  • Focal length: 37.00-68.00
  • F-value: 1.65-1.86
  • Half angle of view: 25.94-14.83
  • Image height: 18.00
  • Total length: 326.49-332.00
  • Back focus: 77.12-83.49

Example 4

  • Focal length: 51.50-97.00
  • F-value: 1.87
  • Half angle of view: 15.59-8.43
  • Image height: 14.37
  • Total length: 204.13-204.12
  • Back focus: 48.80-48.79

Example 5

  • Focal length: 123.60-290.82
  • F-value: 2.89
  • Half angle of view: 9.93-4.25
  • Image height: 21.64
  • Total length: 433.07-433.08
  • Back focus: 54.98-55.00

Canon Patent: RF 24-120mm f/2.8 IS & RF 85mm f/1.4 IS

Canon Patent
View Post

A new Canon patent application for a RF 24-120mm f/2.8 IS and RF 85mm f/1.4 IS lenses.

Canon patent application 2022175604 (Japan, published 11/25/2022) discusses optical formulas for two RF mount lenses, RF 24-120mm f/2.8 IS and RF 85mm f/1.4 IS. From the patent literature:

An object of the present invention is to reduce the size and weight of a movable group decentered with respect to an optical axis, while suppressing the occurrence of chromatic aberration due to the movable group.

Example 1

  • Focal Length: 24.72-116.36
  • F-value: 2.91
  • Half angle of view: 37.12-10.53
  • Image height: 21.64
  • Total length: 178.45-204.02
  • Back focus: 14.59

Example 2

  • Focal length: 82.47
  • F-value: 1.45
  • Half angle of view: 14.70
  • Image height: 21.64
  • Overall length: 126.52
  • Back focus: 13.50

Example 3

  • Focal length: 103.16-387.89
  • F-value: 4.64-7.30
  • Half angle of view: 11.84-3.19
  • Image height: 21.64
  • Total length: 176.10-288.59
  • Back focus: 15.98-63.01

More Canon patent applications are listed here. Some particularly interesting patent applications we think might get into production are these:

[via asobinet.com]

Canon Patent: 35mm And 45mm f/2.8 For Full Frame, And 35mm f/2.8 For APS-C

Canon Patent
View Post

A new Canon patent for more RF mount lenses: 35mm and 45mm f/2.8 for full frame imaging sensors, and a 35mm f/2.8 for APS-C sensors.

Canon patent application P2022163979 (Japan, published 10/27/2022) discusses optical formulas for the following lenses for the RF mount:

  • 35mm f/2.8 (for full frame)
  • 45mm f/2.8 (for full frame)
  • 35mm f/2.8 (for APS-C)

From the patent literature:

A compact and lightweight optical system having high optical performance is provided by appropriately setting the refractive index and power arrangement of each lens.

Description of the Related Art

In recent years, imaging devices have been miniaturized, and the number of pixels of imaging elements used in the imaging devices has increased.

Description of the Related Art

As image pickup devices become smaller and have more pixels, optical systems used in image pickup apparatuses are required to have high optical performance, and to be compact and lightweight.

Example 1

  • Focal Length: 33.13
  • F-value: 2.91
  • Half angle of view: 33.15
  • Image height: 21.64
  • Overall length: 41.51
  • Back focus: 11.50

Example 2

  • Focal length: 34.76
  • F-value: 2.80
  • Half angle of view: 21.45
  • Image height: 13.66
  • Overall length: 40.98
  • Back focus: 13.10

Example 3 

  • Focal length: 46.55
  • F-value: 2.80
  • Half angle of view: 24.93
  • Image height: 21.64
  • Overall length: 53.50
  • Back focus: 14.80

More Canon patent applications are listed here. Some particularly interesting patent applications we think might get into production are these:

[via asobinet]

Canon Patent: RF 28-70mm f/2.8 Lens That Retracts When Zooming

Canon Patent
View Post

Rather interesting Canon patent for a 28-70mm f/2.8 lens that becomes shorter when zoomed to the telephoto end, i.e. it retracts.

Canon patent 2022147945 (Japan, published 10/6/2022) discusses a rather interesting optical formula for a retracting 28-70mm f/2.8 zoom lens for the RF mount. A pretty unique optical design.

From the patent literature:

A zoom lens is provided which is compact and lightweight and capable of achieving high optical performance over the entire zoom range and all object distances.

Example 1

  • Focal length: 28.84-67.90
  • F-value: 2.91
  • Half angle of view: 32.65-17.67
  • Image height: 18.48-21.64
  • Overall length: 149.46-115.94
  • Back focus: 13.48-27.78

Example 2

  • Focal length: 24.72-67.90
  • F-value: 2.91
  • Half angle of view: 35.02-17.67
  • Image height: 17.32-21.64
  • Overall length: 150.00-130.39
  • Back focus: 9.87-27.17

Example 3

  • Focal length: 28.84-67.90
  • F-value: 2.91
  • Half angle of view: 34.77-17.67
  • Image height: 20.02-21.64
  • Overall length: 152.61-120.01
  • Back focus: 22.71-41.28

More Canon patent applications are listed here. Some particularly interesting patent applications we think might get into production are these:

[via asobinet]

Canon Patent: 300mm f/2.8, 400mm f/2.8 And 600mm f/4 With Built-in Teleconverter

Canon Patent
View Post

A new Canon patent for telephoto lenses with built-in teleconverter. For what mount? RF mount.

Canon patent 2022142979 (Japan, published 10/3/2022) discusses optical formulas for three telephoto lenses with built-in teleconverter. The lenses are 300mm f/2.8, 400mm f/2.8 and 600mm f/2.8. From the patent literature (machine translated):

An object of the present invention is to provide an optical system having a variable power optical system that is inserted into and removed from a main optical system, and to achieve good optical performance while reducing the weight of the entire system.

Description of the Related Art

As a method for changing the focal length of an optical system used in an imaging apparatus, there is a converter method that changes the focal length of the entire system by inserting a variable magnification optical system (extender) in the optical path.

When adopting a system incorporating a variable magnification optical system, in order to achieve good optical performance while reducing the weight of the entire system including the variable magnification optical system, the insertion position of the variable magnification optical system must be appropriately selected. It is important not only to do so, but also to properly configure the main optical system. The invention disclosed in Patent Document 1 has room for improvement from the viewpoint of achieving both weight reduction and optical performance.

Summary of the invention

It is an object of the present invention to achieve good optical performance while reducing the weight of the entire system in an optical system having a variable magnification optical system that is inserted into and removed from a main optical system.

Example 1 ML

  • Focal length: 389.00
  • F-value: 2.91
  • Half angle of view: 3.18
  • Image height: 21.64
  • Total length: 406.00
  • Back focus: 53.83

Example 1 with teleconverter

  • Focal length: 544.00
  • F-value: 4.19
  • Half angle of view: 2.28
  • Image height: 21.64
  • Overall length: 406.01
  • Back focus: 53.83

Example 2 ML

  • Focal length: 582.00
  • F-value: 4.12
  • Half angle of view: 2.13
  • Image height: 21.64
  • Overall length: 486.10
  • Back focus: 81.91

Example 2 with teleconverter

  • Focal length: 814.80
  • F-value: 5.88
  • Half angle of view: 1.52
  • Image height: 21.64
  • Overall length: 486.10
  • Back focus: 81.91

More Canon patents are listed here.

[via asobinet]

Canon Patent: 16mm f/2.8 & 20mm f/2.8 With Image Stabilization

Canon Patent
View Post

A new Canon patent to start a new week. Once more for lenses for the RF mount.

Canon patent 2022125455 (Japan, published 8/29/2022) discusses optical formulas for two prime lenses, a 16mm f/2.8 and a 20mm f/2.8, both with image stabilisation. From the patent literature (machine translated):

[Title of Invention] Optical system, lens device having the same, and imaging device

The present invention provides an optical system having a wide angle of view, a small size and light weight, and high optical performance in the non-stabilizing state while suppressing peripheral image quality deterioration during image blur correction, and a lens device and an imaging device having the same.

Description of the Related Art

Conventionally, as means for correcting image blurring, there are known a lens-shift type anti-vibration mechanism that shifts a part of an optical system and a sensor-shift type anti-vibration mechanism that shifts an imaging device. In a central projection optical system, the amount of movement of the image point in response to changes in the angle of incidence of light rays entering the optical system is not uniform on the imaging surface. However, image blur remains around the imaging surface.

The imaging apparatus of Patent Document 1 can correct image blur at a specific image point position, but cannot uniformly correct image blur at all angles of view.

In an equidistant projection optical system, the image quality around the imaging surface is less likely to deteriorate during image blur correction. Therefore, in order to suppress image quality deterioration around the imaging surface, it is necessary to generate a large amount of distortion in the negative direction in the central projection method, and reduce the absolute value of the amount of distortion in the equidistant projection method.

An optical system with a large absolute value of the amount of distortion aberration in the central projection method produces a greatly distorted image, so it is often used in combination with an imaging apparatus equipped with electronic distortion correction. In this case, if the distortion aberration in the central projection method is excessively generated, the image quality around the imaging surface is degraded due to the extension of the electronic distortion correction.

Example 1

  • Focal length: 24.22
  • F-value: 1.85
  • Image height: 19.38
  • Overall length: 85.24
  • Back focus: 12.06

Example 2

  • Focal length: 19.48
  • F value: 2.88:
  • Image height: 18.60
  • Overall length: 73.01
  • Back focus: 12.19

More Canon patent applications are listed here. Some particularly interesting patent applications we think might get into production are these:

[via asobinet]