Canon Patent To Improve AF In Lenses With Reflective Optics

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A new Canon patent was spotted. Autofocus improvement for mirror lenses, i.e. lenses with a reflective optical system.

Canon patent application 2022103610 (Japan) discusses methods and technologies to improve autofocus on mirror lenses.

PROBLEM TO BE SOLVED: To provide a lens device capable of detecting an accurate defocus amount when a reflective optical system is used.

However, in the configurations disclosed in Patent Documents 1 and 2, when the central portion of the light flux is shielded by the reflective telephoto lens (catadioptric system), the image signal corresponds to the change in the vignetting direction of the AF light flux. The correction and the calculation of the conversion coefficient are not performed, and a focus detection error occurs.

Therefore, it is an object of the present invention to provide a lens device, an image pickup device, a control method of the lens device, and a program capable of detecting an accurate defocus amount when a reflective optical system is used.

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

[via asobinet]

Canon Patent: Super Small 28-70mm f/2.8 & 28-60mm f/2.8 Lenses For RF Mount

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A new and rather interesting Canon patent application. Very compact zoom lenses with large aperture.

Canon patent application 2022091621 (Japan) discusses optical formulas for two small and compact zoom lenses with large aperture:

  • 28-70mm f/2.8
  • 28-60mm f/2.8

From the patent literature:

PROBLEM TO BE SOLVED: To provide a zoom lens having a short total length and a small size but having high optical performance, and an image pickup apparatus having the same.

In recent years, with the increasing functionality of image pickup devices, there is a demand for a compact and lightweight zoom lens having a large aperture ratio. As a zoom lens that satisfies this requirement, a negative lead type zoom lens in which a lens group having a negative refractive power is arranged on the object side is known (see Patent Document 1 and Patent Document 2).

In the zoom lens of Patent Document 1, the refractive power of the first lens group is strengthened, and the movement locus of the first lens group during zooming becomes a substantially reciprocating locus, so that the total length of the zoom lens at the telephoto end can be increased. become longer. In addition, the back focus is long, and it is difficult to shorten the total length of the zoom lens. Further, the thickness of the first lens group becomes large due to the aberration correction in the first lens group, which is not preferable from the viewpoint of miniaturization and weight reduction.

In the zoom lens of Patent Document 2, the refractive power of the first lens group is strong in order to obtain a zoom magnification, and the configuration of the subsequent group is a four-group configuration up to the fourth lens group. If a larger aperture ratio is aimed at, it will not be possible to suppress various aberrations and zoom fluctuations of aberrations in the telephoto region, and it will be difficult to satisfy good optical performance over the entire zoom range.

An object of the present invention is to provide a zoom lens having a short overall length, a small size, and high optical performance, and an image pickup apparatus having the same.

In the zoom lens of each embodiment, in order to ensure good optical performance even at a close object distance, two or more lens groups among the lens groups arranged on the image side of the first lens group L1 are focused. It is preferable to have a so-called floating configuration in which the lens moves at the time.

Example 1

  • Focal length: 28.84-67.90
  • F value: 2.91
  • Half angle of view: 32.68-17.67
  • Image height: 18.50-21.64
  • Overall length: 138.40-105.42
  • Back focus: 10.97-21.12

Example 2

  • Focal length: 28.84-60
  • F value: 2.91
  • Half angle of view: 32.68-19.83
  • Image height: 18.50-21.64
  • Overall length: 132.38-106.85
  • Back focus: 13.47-23.82

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

[via asobinet]

Canon Patent: 135mm f/2, 400mm f/4 and 50mm f/2.5 With Defocus Smoothing

Defocus Smoothing
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Very interesting Canon patent application: a set of RF mount lenses with electronically controlled Defocus Smoothing (DS).

Defocus Smoothing is a technology Canon first introduced with the RF 85mm f/1.2L DS lens (see here for our coverage). The featured Canon patent might suggest more DS lenses are on their way.

Canon patent application 2020-199390 (Japan) discusses optical formulas and methods for three prime lenses with DS:

  • 135mm f/2
  • 400mm f/4
  • 50mm f/2.5

From the patent literature:

PROBLEM TO BE SOLVED: To provide an optical device capable of sufficiently adjusting the clarity of the outline of a blur even if the aperture diameter of a diaphragm is greatly changed.

BACKGROUND ART: Conventionally, an image formed by an optical device may be required to include a blur with a smooth outline, or may include a blur with a clear outline. May be required.

Patent Document 1 discloses an optical device capable of smoothing or clarifying the outline of blur by providing an optical element capable of reversibly switching the distribution of transmittance. The clarity of the outline of the blur is required to be sufficiently adjustable even when the aperture diameter of the diaphragm is greatly changed.

However, the optical device disclosed in Patent Document 1 is insufficient to meet the above-mentioned requirements because the clarity of the outline of the blur can be sufficiently adjusted only in the vicinity of the opening of the aperture.
Therefore, an object of the present invention is to provide an optical device capable of sufficiently adjusting the clarity of the outline of a blur even if the aperture diameter of the diaphragm is greatly changed. In various optical systems such as photographic and video lenses, not only the characteristics of the image plane but also the image quality of the out-of-focus portion, that is, the quality of blur may be emphasized.

In general, there are cases where a smooth blur that melts without a clear outline is desired, and there are cases where a blur with a clear outline is desired. As a method of changing the contour of the blur, for example, a method of inserting an apodization filter whose transmittance decreases as the distance from the optical axis increases is known.

As a result, the transmittance distribution of the apodization filter is superimposed on the blurred image, and smooth blurring such that the contour melts can be realized. However, when the apodization filter is inserted, the outline of the blur is always smooth in the vicinity of the opening of the aperture, so that it becomes difficult to clarify the outline of the blur according to the request.

Further, when the apodization filter is inserted, the amount of transmitted light in the optical system is reduced, so that the demerit of inserting the apodization filter becomes greater in the shooting scene where almost no blurring occurs in the screen.
Therefore, there is also known a method of switching the apodization effect on and off by using an optical element capable of reversibly controlling the distribution of the transmittance, that is, adjusting the clarity of the outline of the blur according to a request.

Example 1

  • Focal length: 133.05
  • F value: 2.06
  • Half angle of view: 9.24
  • Image height: 21.64
  • Overall length: 170.39
  • Back focus: 45.96

Example 2

  • Focal length: 399.84
  • F value: 4.00
  • Half angle of view: 3.10
  • Image height: 21.64
  • Overall length: 298.46
  • Back focus: 145.16

Example 3

  • Focal length: 49.00
  • F value: 2.50
  • Half angle of view: 23.82
  • Image height: 21.64
  • Overall length: 68.15
  • Back focus: 11.00

The following, short video tells what Defocus Smoothing is:

[via asobinet]

Canon Patent: 11-24mm f/4 IS, 12-24mm f/2.8 IS, And Already Released RF 14-35mm f/4L IS

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A new week, a new Canon patent application. More lenses for the RF mount and one already released lens.

Canon patent application 2020-199535 (Japan) seems to describe the optical formula for the already released RF 14-35mm f/4L IS, and for two more wide angle zoom lenses for the RF mount: 11-24mm f/4 IS and 12-24mm f/2.8 IS.

PROBLEM TO BE SOLVED: To provide a zoom lens capable of achieving both wide angle of view and miniaturization, and further maintaining high optical performance even at the time of vibration isolation.

Example 1

  • Focal length: 11.33-23.30
  • F value: 4.08
  • Half angle of view: 59.63-42.88
  • Image height: 19.33-21.64
  • Overall length: 135.40-130.90
  • Back focus: 13.63-14.26

Example 2

  • Focal length: 12.36-23.30
  • F value: 2.91
  • Half angle of view: 57.41-42.88
  • Image height: 19.33-21.64
  • Overall length: 130.51-119.64
  • Back focus: 13.43-24.55

Example 3

  • Focal length: 14.42-33.95
  • F value: 4.08-4.12
  • Half angle of view: 53.26-32.50
  • Image height: 19.33-21.64
  • Overall length: 125.87
  • Back focus: 14.99

Example 4

  • Focal length: 15.45-33.95
  • F value: 2.91
  • Half angle of view: 51.37-32.51
  • Image height: 19.33-21.64
  • Overall length: 149.62-135.96
  • Back focus: 15.11

More Canon patent applications are listed here. 

[via asobinet]

Canon Patent: RF 11-24mm f/4L & RF 8-24mm f/4L Fisheye

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A new Canon patent application surfaced. It’s for RF lenses, as most of the recent Canon patents for lenses are.

Canon patent application 20220171174 (USA) discusses optical formulas for a RF 11-24mm f/4L lens.

  • Focal Length: 11.33mm – 23.30mm
  • F-Number: 4.08
  • Half Angle of View: 59.63° – 42.88°
  • Image Height: 21.64mm

Canon patent application 20220171172 (USA) discusses optical formulas for a RF 8-24mm f/4L fisheye lens.

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

[via Canon Rumors]

Canon Patent: 14mm, 16mm, 18mm, 20mm f/2.8 Lenses For Mirrorless System

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A new week, a new Canon patent application. Like prime lenses? Here are a bunch that might be available soon.

Canon patent application P2022085382 (Japan) discusses optical formulas for the following prime lenses for the RF mount:

  • 14mm f/2.8
  • 16mm f/2.8
  • 18mm f/2.8
  • 20mm f/2.8

PROBLEM TO BE SOLVED: To provide an optical system having high optical performance in a small size and light weight in a wide-angle lens, and an image pickup apparatus having the same.

BACKGROUND ART: As a shooting optical system having a wide shooting angle, an optical system having a negative refractive power is arranged on the object side, and an optical system having a positive refractive power is arranged on the image side, so-called retrofocus. A type of photographic optical system is known and is used, for example, in a single focus wide-angle lens.

Further, in digital cameras and video cameras, the number of pixels of solid-state image sensors such as CCDs and CMOS sensors is increasing, and high optical performance including chromatic aberration is required for photographing lenses, and miniaturization is also progressing.

In recent years, in a wide-angle lens system used in an image pickup apparatus, a wide angle of view is required in order to enable shooting in a wider range while the entire lens is small.

Generally, in a wide-angle lens, a wide angle of view is realized by arranging an optical system having a negative refractive power on the object side. In order to widen the angle of view, it is necessary to increase the negative refractive power on the object side, but as the radius of curvature of the lens becomes smaller, the lens processing accuracy deteriorates and the image generated mainly by off-axis rays It causes curvature of field and deterioration of chromatic aberration of magnification. In order to solve these problems, it is necessary to increase the lens diameter on the object side and increase the number of lenses, which is not preferable. In order to reduce the lens diameter, widen the angle of view, and achieve high optical performance, it is necessary to properly arrange the aperture and appropriately arrange the negative refractive power of the optical system arranged on the object side of the aperture. You will need it.

Example 1

  • Focal length: 18.20
  • F value: 2.90
  • Half angle of view: 45.00
  • Image height: 18.20
  • Overall length: 63.45
  • Back focus: 12.94

Example 2

  • Focal length: 14.28
  • F value: 2.91
  • Half angle of view: 51.88
  • Image height: 18.20
  • Overall length: 57.50
  • Back focus: 10.97

Example 3

  • Focal length: 16.48
  • F value: 2.90
  • Half angle of view: 47.84
  • Image height: 18.20
  • Overall length: 63.19
  • Back focus: 12.54

Example 4

  • Focal length: 20.10
  • F value: 2.91
  • Half angle of view: 42.16
  • Image height: 18.20
  • Overall length: 63.55
  • Back focus: 14.51

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

[via asobinet.com]