Canon Patent For 400mm f/4 DO Lens

Canon Patent

Canon Patent

Egami (translated) spotted another patent filed by Canon. It is for a 400mm f/4 lens with diffractive optical elements (to reduce flare).

Patent description (machine translated):

  • Patent Publication No. 2013-64858
    • 2013.4.11 Release Date
    • Filing date 2011.9.16
  • Example 1
    • Focal length f = 392.12mm
    • Fno. 4.12
    • Half angle of ω = 3.16 °
    • Image height Y = 21.64mm
    • 262.14mm length lens
    • BF 69.97mm
    • Two fluorite
  • Materials and anomalous partial dispersion DOE to use, reduce the chromatic aberration
  • Refractive power of the diffractive surface
    • Strong, but can reduce the chromatic aberration of the element itself, flare increases
    • The weaker, other optical element DOE play a role
  • Refractive optical unit
    • DOE anomalous partial dispersion and bonding materials
    • DOE aspherical surface on the opposite side of the
  • Vibration control
  • Inner Focus
[via Egami]

Canon Files Patent For New Primes (45mm, 50mm, 60mm)

50mm f/1.4
50mm f/1.2

Egami spotted another patent filed by Canon. The patent refers to s 50 mm F1.4 , 50 mm F1.2 , 45mm F1.6 and 60 mm F1.8 lenses, and describes an apochromatic design that aims to reduce chromatic aberration.

Patent description (machine translated):

  • Patent Publication No. 2013-57802
    • 2013.3.28 Release Date
    • 2011.9.8 filing date
  • Example
    Focal length Fno. Angle of view Focus
    One 51.7 1.45 45.4 Floating rear focusing +
    Two 51.7 1.45 45.4 Fed whole
    Three 51.7 1.25 45.4 Floating rear focusing +
    Four 51.7 1.25 45.4 Fed whole
    Five 45.0 1.6 51.4 Fed whole
    Six 60.0 1.85 39.7 Fed whole
  • In many large-diameter Gaussian secondary spectrum of axial chromatic aberration
    • This problem occurs when using glass and others with the same Abbe number, a lens that is different partial dispersion ratio
    • When used in a positive lens lanthanum flint glass small partial dispersion ratio
    • When used in a negative lens of flint glass titanium large partial dispersion ratio
  • Canon patent
    • Using a lens with a partial dispersion ratio appropriate correcting the axial chromatic aberration secondary spectrum
    • The concave lens surface adjacent to the aperture, coma aberration correction, the sagittal flare
[via egami]

Patent For New Canon 14mm f/2.8 With Improved Surface Coating

Canon 14mm f/2.8

Canon 14mm f/2.8

Egami (translated) found a patent filed by Canon for a 14mm f/2.8 lens with a new anti-reflective coating, Subwavelength Structure Coating. This method optimizes the refractive index and allows for a thinner anti-reflective film.

Appears as if Canon is working on a successor of the EF 14mm f/2.8L II USM lens (price & specs).

Patent specification (machine translated):

  • Patent Publication No. 2013-47780
    • 2013.3.7 Release Date
    • Filing date 2011.7.26
  • Example
    • F = 14.3mm focal length
    • Half angle ω = 56.6 °
    • Fno. 2.89
    • 14 images in 10 groups lens configuration
  • Canon patent
    • Antireflection film which is excellent in productivity and reflectance characteristics
    • The refractive index of the substrate (original surface of the lens) is 1.65 to 2.20
    • Consists of three layers, the ratio of the refractive index change with a three-layer
    • The third layer
      • Average roughness of less than 400nm pitch structure
      • By continuously varying the ratio of the space-filling structure uneven, changing the refractive index
      • After drying, the film is immersed in hot water and applied to the second layer solution (containing aluminum oxide) by spin coating, plate-like crystals deposited on the surface
    • If spin coating of the wet process, excellent in productivity can be realized a uniform thickness
    • Little change in the characteristics even if there is variation in thickness


Canon Patent For New Mount Type (non rotating elements when lens is not mounted)

Canon Patent For New Mount Type
Courtesy: Egami

Egami (translated) spotted an interesting patent filed by Canon. When mounting a lens on a camera body, and holding the lens, the rotating focus or zoom ring can make the operation more difficult. Imagine you have to switch lenses fast, the rotating elements of the lens can slow down the mounting of the lens. The Canon patent is for a new lens mount type that blocks all rotating elements of a lens when the lens is not mounted on a body, hence making mounting the lens easier (and faster). This is achieved by pins on the lens mount that block the rotating members inside the lens barrel. The new mount type is compatible with existing EOS mounts. That means lenses that will feature this new kind of mount can be used with existing EOS bodies.

Patent description (machine translated)

  • Patent Publication No. 2013-37090
    • 2013.2.21 Release Date
    • 2011.8.5 filing date
  • Rotatable operation unit: a rotating member
    • Ring, other zoom ring, focus ring, aperture
  • Canon patent
    • If you remove the lens from the camera, the rotation is restricted
      • Pins are provided on the surface of the lens mount
      • The boss is attached to (inside the lens barrel) end of the pin
      • Inside the lens barrel, the boss is brought into contact with the rotating member
      • Because of the boss, the rotating member is rotated never
    • When mounted on the camera lens, rotatable
      • Pin is provided on the mounting side of the body
        • Etc. F or mount EOS mount, mount a lot of this method
      • Body side pin, and push the pin on the lens, the position of boss will move
      • To the rotating member does not contact the boss, can be rotated

Canon Patent For Two New Fluorite Treated Lenses

Canon Patent
17-35mm f/2.8-4
Canon Patent
14mm f/2.8

Egami (translated) spotted a patent referring to two new lenses, a 14mm f/2.8 and a 17-35mm f/2.8-4, both with fluorite treatment. According to WIkipedia…:

Fluorite (also called fluorspar) is a halide mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon. Crystal twinning is common and adds complexity to the observed crystal habits.


Optically clear transparent fluorite lenses have low dispersion, so lenses made from it exhibit less chromatic aberration, making them valuable in microscopes and telescopes. Fluorite optics are also usable in the far-ultraviolet range where conventional glasses are too absorbent for use.

Click here to see a Canon video about fluorite and lenses.

The patent:

  • Patent Publication No. 2013-37339
    • 2013.2.21 Release Date
    • Filing date 2011.7.12
  • Example 1
    • Zoom ratio 1.00
    • Focal length f = 1.00mm
    • Fno. 2.90
    • Half angle of view ω = 56.66 °
    • Image height Y = 1.52mm
    • 9.51mm length lens
    • BF 2.82mm
    • 6 aspherical surfaces, the first surface 25
    • Punctually
  • Example 3
    • Zoom ratio 2.06
    • 2.06mm – f = 1.00 focal length
    • Fno 2.79 -. 4.00
    • Half angle of view ω = 51.27 – 32.82 °
    • 1.33mm – Y = 1.25 image height
    • 8.55mm – 8.79 length lens
    • BF 2.41 – 3.46mm
    • Aspheric first surface, the fifth surface, the first surface 26
    • Positive and negative positive negative
  • Example 6
    • Zoom ratio 1.00
    • Focal length f = 1.00mm
    • Fno. 2.90
    • Half angle of view ω = 87.35 °
    • Image height Y = 21.60mm
    • 9.51mm length lens
    • BF 2.82mm
    • 6 aspherical surfaces, the first surface 25
    • Punctually

Canon Patent For Second Row Of Electronic Contacts

Canon Patent

Canon Patent

Egami (translated) spotted a Canon patent concerning a second row of electronic contacts on the lens mount. The patent suggests the second row of contacts is dedicated to the video signal, avoiding loss of signal strength could be the reason (the video signal needs more power supply).

  • Patent Publication No. 2013-21391
    • 2013.1.31 Release Date
    • 2011.7.7 filing date
  • Canon patent
    • In addition to the conventional first electronic contact, provided new second electronic contacts
    • Contact each other first and second non-overlapping so that
    • Corresponding to the new system
      • In addition to the video sync signal
      • In the serial clock, eliminating the need for transformation of the communication level
      • Because the focus of video requires a larger power supply