Is Canon Developing A Mirror Lens With Auto-Focus?

Canon Patent
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That’s what a Canon patent application seems to suggest, a 300mm f/2.3 mirror lens. Read on.

Canon patent application 2023013456 (Japan, published 1/26/2023) discusses optical formulas for a 300mm f/2.3 mirror lens with autofocus. From the patent literature:

An optical system capable of sufficiently correcting curvature of field while being compact, lightweight, and having a large aperture ratio is provided.

Description of the Related Art

As a telephoto imaging optical system having a long focal length, there is a catadioptric imaging optical system having a reflective system and a refracting system. In such a catadioptric imaging optical system, Patent Literatures 1 and 2 disclose an inner focus type imaging optical system that is compact, lightweight, has a large aperture ratio, and has an autofocus function. ing. [0004]However, in the imaging optical systems disclosed in Patent Documents 1 and 2, the configuration of the reflection system cannot sufficiently correct the curvature of field.

SUMMARY OF THE INVENTION

The present invention provides an optical system capable of sufficiently correcting curvature of field while having a small size, light weight, and large aperture ratio.

An optical system as one aspect of the present invention has a first group that does not move during focusing and a second group that moves during focusing.

Example 1

  • Focal length: 298.89
  • F-value: 2.28
  • Half angle of view: 4.14
  • Image height: 21.64
  • Overall length: 177.20
  • Back focus: 65.95

Example 2

  • Focal length: 408.04
  • F-value: 5.00
  • Half angle of view: 3.04
  • Image height: 21.64
  • Total length: 189.17
  • Back focus: 47.69

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
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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 RF 300mm f/2.8L IS To Get Announced Soon?

Nab 2023 Canon Eos R5 Mark Ii Canon Eos R8 Mark Ii Canon EOS Rf 24-50mm R6 Mark Ii Rf Mount Eos R6 Mark Ii Rf 300mm Rf 35mm Canon Eos R100 Rf 24mm F/1.8 Rf-s Canon Eos R7 Eos R100 Canon High Resolution Eos R R10 Eos C5 Canon Canon Eos R1 Eos R5c Canon Rf 16mm Rf 35mm F/1.2L EF Lenses Tilt-shift Lenses Rumor
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A new rumor, about the Canon RF 300mm f/2.8L IS lens. Is it coming? The EF version is discontinued.

A rather confident rumor suggests that Canon might be close to announce the Canon RF 300mm f/2.8L IS lens. Says the source of the rumor:

[…] Canon has prototypes out in the wild and that the lens is a ground-up redesign of the focal length.

[…] weight has been reduced by almost 40% and  the length by as much as 30% over it’s EF predecessor, though they didn’t have the exact dimensions and weight to give us.

The lens is rumored to get announced at the beginning of 2023.

Stay tuned.

Source: Canon Rumors

Canon Patent: 200mm f/2, 300mm f/2.8 And 500mm f/4 (RF mount?)

Canon Patent
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Canon patent application for some telephoto zooms, for the EOS R system I guess.

Canon patent application 2020196094 (Japan) discusses optical formulas for three telephoto zoom lenses:

  • 200mm f/2
  • 300mm f/2.8
  • 500mm f/4

As a shooting optical system having a long focal length, a so-called telephoto type shooting optical system is known. The telephoto type photographic optical system is used, for example, in a single focus super-telephoto lens.

In the photographing optical system described in Patent Document 1, the second lens group having a negative refractive power is moved during focusing. Here, the second lens group is arranged at a position relatively close to the first lens group, and it cannot be said that the focus group can be sufficiently reduced in size and weight.

An object of the present invention is to provide an optical system that is lightweight and has chromatic aberration and other aberrations satisfactorily corrected, and an image pickup apparatus having the same.

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

[via Digicame Info]

Olympus 300mm f/4 vs Canon RF 600mm f/11 – FF vs 4/3 Comparison

Olympus 300mm
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Somewhat unusual yet rather interesting comparison between the Olympus 300mm f/4 and Canon RF 600mm f/11 lenses.

Our friends at Mirrorless Comparison compared the Olympus 300mm f/4 and Canon RF 600mm f/11 lenses for wildlife and bird photography. The former is for Micro Four Thirds and the latter for full frame. From their conclusion:

Traditionally, micro four thirds has always been the system we mention when talking about travelling light and reducing size and weight. On the other hand, full frame is supposed to be the system with the big heavy lenses, but also superior image quality. Well, in our case here, some of these claims can be challenged (with a few catches).

The RF 600mm F11 (and 800mm F11) is a brilliant idea from Canon. I was interested when they announced it, then I was skeptical about the aperture, but now I’m happy to say I really enjoyed taking pictures with this lens, and I quickly forgot about the slow aperture. I was using something very light, with excellent quality, autofocus and stabilisation. I thought there would be more tradeoffs than that.

[…]

Where does that leave the Olympus solution then? Well, rest assured, it is still a very strong competitor. The faster aperture of the 300mm Pro easily makes up for the smaller sensor, you get a premium build quality with weather sealing, state of the art stabilisation and a few welcome features like being able to focus much closer to small subjects, which adds to the lens’ versatility.

Read the review at Mirrorless Comparison

More comparison reviews are listed here.

More Big White Telephoto Lenses Coming To The Canon EOS R System, Next Year

Telephoto
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No surprise that after the leaks of the last days more telephoto lenses for the RF mount are rumored. Nothing to expect for this year, though.

Canon might be set to release an RF 300mm f/2.8L IS and an RF 500mm f/4L IS lens in 2021. Canon is migrating more and more of their EF lenses to the RF mount.

The RF 300mm f/2.8L IS and an RF 500mm f/4L IS are said to be much lighter and also shorter than their EF mount counterparts. A 300mm f/2.8L IS zoom might also be in the works.

Source: Canon Rumors