[Patent] Canon Files Patent For 14mm f/2.8 Lens (better coating, low refractive index)

14mm f/2.8

Egami (translated) spotted another patent filed by Canon. This time it is for a 14mm f/2.8 lens with improved coating (tubular coating):

It seems it is possible to realize a low-refractive-index low reflectivity by the structure below the diffraction limit, even without the uneven surface of the coating. 14mm F2.8 is what I want you to adopt all means patent coating of the lens as the front lens is large, yet is protruding.

Cross-sectional view
  • Patent Publication No. 2012-159723
    • 2012.8.23 Release Date
    • 2011.2.1 filing date
  • Example 1
    • F = 14.3mm focal length
    • Fno. = 2.89
    • Half angle ω = 56.6 °
    • 14 images in 10 groups lens configuration
  • Existing coating roughness
    • In daily use, dirt or dust may adhere, could not wipe, sex or bad Mentenasu productivity and manufacturing process
  • Canon patent
    • (Coating applied to one surface of a lens) thin film layer
    • Having a plurality of tubular spaces are arranged parallel to the tube
    • Maximum opening diameter of the tubular space below 400nm
    • The inorganic oxide materials (silica, titania)
[via Egami]

Canon Files Patent For 28-300mm and 28-135mm lens (reduced chromatic aberrations)

28-300mm f/3.5-5.6
28-135mm f/4-5.6

Next two Canon patents! As usual spotted by Japanese site Egami (translated) This time for a 28-135mm f/4-5.6 and a 28-300mm f/3.5-5.6 lens.The patent is about reducing chromatic aberrations.

  • Patent Publication No. 2012-163746
    • 2012.8.30 Release Date
    • 2011.2.7 filing date
  • Example 4
    • Zoom ratio 4.67
    • 56.11 – – 131.85mm f = 28.21 focal length
    • Fno 4.12 -. 4.89 – 5.77
    • Half angle of view ω = 37.48 – 21.09 – 9.32deg.
    • Image height 21.64mm
    • 242.67 – – 266.43mm 224.00 overall length of the lens
    • BF 55.79 – 70.40 – 82.95mm
    • 20 sheets of 14 group lens configuration
    • Two two-sided aspherical
    • Three low-dispersion glass
    • Four Super UD glass
    • 102.40mm effective diameter of the first surface
    • 5-group zoom negative positive negative
  • Example 5
    • Zoom ratio 10.31
    • 93.64 – – 307.06mm f = 29.77 focal length
    • Fno 3.31 -. 4.71 – 5.85
    • Half angle of view ω = 36.00 – 13.01 – 4.03deg.
    • Image height 21.64mm
    • 263.66 – – 304.01mm 209.34 overall length of the lens
    • BF 61.72 – 89.40 – 106.84mm
    • 18 sheets 12 groups lens configuration
    • Three 3 aspherical surface
    • Three low-dispersion glass
    • 2 UD glass sheets
    • 84.36mm effective diameter of the first surface
    • 5-group zoom negative positive negative
  • In the zoom lens of the positive lead type, reducing the chromatic aberration of magnification of the secondary

More graphs after the break

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Canon Patent To Reduce Ghosting And Flaring (14mm f/2.8)

14mm f/2.8

Once more great Japanese site Egami (translated) spotted an important Canon patent. It is about the reduction of ghosting through anti-reflective coating on both sides of the lens, the coating consisting of fine uneven structures. Ghosting happens for instance when you point your lens at a bright light source, like the sun, and are the result of an acute angle of light bouncing (reflecting) between the individual glass elements of the lens. The technology is filed using a 14mm f/2.8 lens as engineering example. Should work well on other wide angle lenses too.

Surface coating
  • Patent Publication No. 2012-159720
    • 2012.8.23 Release Date
    • 2011.2.1 filing date
  • Example 1
    • F = 14.3mm focal length
    • Fno. = 2.89
    • Half angle of view ω = 56.5deg.
    • 14 images in 10 groups lens configuration
    • 1 UD glass sheet
  • Canon patent
    • Suppress the occurrence of the ghost
    • Having two surface anti-reflection surface of fine uneven structure
      • Non-periodic pitch
      • 400nm 300nm pitch less than average
    • Incident light for various interference conditions to cancel the reflected light is maintained
    • The average height of uneven surface with two different
    • 0.001% or less (2) the product of the reflectance of the surface (incident angle 0 degree)
    • 0.1% or less (2) the product of the reflectance of the surface (incident angle 60 degrees)
    • 0.05% more than the absolute value of the difference between the reflectance of the surface (2), (0 ° angle of incidence)
    • 0.2% or more the absolute value of the difference in reflectance of the surface (2), (incident angle 60 degrees)
    • The anti-reflection film of aluminum and aluminum oxide
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Canon Files Patent For A 300mm f/4 Lens

Egami (translated) spotted a Canon patent for a 300mm f/4 lens, the possible successor of the EF 300mm f/4L IS USM (?). The patent suggests that performance fluctuations that are due to temperature changes, and chromatic aberrations have been reduced. The patent is about a light lens, with lots of plastics to keep the weight down. The patent also suggests a small lens with an overall length of 221mm.

This patent is to contribute to miniaturization, become = 300×0.68 = 204mm optical length simple calculation, pull the flange back of EOS, and = 204-44 = 160mm length products. So product length 221mm

  • Patent Publication No. 2012-159726
    • 2012.8.23 Release Date
    • 2011.2.1 filing date
  • Example 3
    • F = 300mm focal length
    • Fno. 4.0
    • Tele ratio 0.68
    • Inner Focus
    • φr = 68.8mm
    • φg1 = 67.8mm
    • φg2 = 70.2mm
  • Technical background
    • When the miniaturization of the optical system, longitudinal chromatic aberration, chromatic aberration of magnification is remarkable
    • As the focal length becomes longer, the telephoto lens system, chromatic aberration is noticeable
    • There is a method of correcting the aberrations of a material having an anomalous dispersion resin, the resin is difficult to produce high-precision thick
    • There is a method of sandwiching a thin glass resin material, the bonding peeling distortion problem bonding at high temperature
  • Canonpatent
    • Joining three or more optical elements
    • The outer diameter of the resin is increased to reduce the distortion at the time of bonding
      • Not adhere to each other resin outer glass element
      • Between the optical element of the outside is gone, adhesive, the thickness of the adhesive distribution occurs
    • Using a sealing agent to prevent change in shape of the resin and the refractive index change due to moisture absorption
    • Do the black outer peripheral portion of the glass element
      • Prevent flare and ghosting resin at the outer periphery
      • Surface resin glue is not good
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[Patent] Another Canon Patent For Improved Phase-Detection Autofocus (next mirrorless sensor?)

Conventional approach (left) and patented approach (right)

Egami (machine translated) spotted another patent filed by Canon and related to methods that aim to improve the performance and accuracy of the phase-detection AF. This is the second patent in a few days – the first one can be seen here. Such an AF method is featured on the Rebel T4i/650D and on Canon’s recently announced mirrorless camera, the EOS M. Note that such an AF method is particularly useful on a mirrorless camera, given that such cameras, since they are missing the mirror, can not focus in the “traditional way”.

As far as I can tell, the patent details methods to increase AF performance by eliminating problems caused by the angle of incidence of the light: “[…] reduce the diffraction limit by a high refractive index layer“. Another discussed issue is the reduction of the pixel size (higher resolution??). I am more and more confident that both patents are related to an upcoming sensor which, I guess, will be at the heart of the more pro-oriented mirrorless camera most of us are expecting to be announced in September at Photokina.

  • Patent Publication No. 2012-151367
    • 2012.8.9 Release Date
    • 2011.1.20 filing date
  • The diameter of the spot light focusing of the micro lens
    • Determined by the numerical aperture and λ the wavelength of the incident light
    • By the wave nature of light, not smaller than the diffraction limit
    • When the pixel size below the diffraction limit, pupil division is impossible
    • ⊿ = 1.22 * (λ / n * sinθ) diffraction limit
    • ※ This angle θ is half the chance of lens optical system was synthesized in the micro-lenses and layers
  • Related art
    • There is a light flux can not reach into the openings of the light-shielding layer of the phase difference AF pixel for the image plane, the light-receiving efficiency is reduced
    • Although the distance can be shortened and the photoelectric conversion unit if microlens back-illuminated (BSI), if the pixel consists of a low refractive index layer in the layer lens +, for total internal reflection occurs, can not be expected to increase the angle
  • Canon’s patented
    • To reduce the diffraction limit by a high refractive index layer
    • Structure of the pixel
      • Within a layer lens, and light shielding layer formed between the microlens
      • The high refractive index layer, filled between the lens and the light-shielding layer in the layer
      • The low refractive index layer, a light shielding layer filled between the microlens and
      • Optical system consisting of micro-lens and lens in the layer, connecting the focal point in the PD
      • A case
        • Λ = 540nm wavelength of the incident light
        • 1.6 refractive index of the microlens
        • 1.45 refractive index of the low refractive index layer
        • Layer of high refractive index lens and in the layer refractive index n = 2.3 (silica Sio 2 of the prior art is n = 1.46)
[via egami]

[Patent] New Canon Phase-Detection AF Method With Higher Accuracy And Smaller Pixel Size (for the next mirrorless camera?)

Egami (machine translated) found a Canon patent for an improved phase-detection AF. Higher accuracy is obtained by better propagation of light. The patent text also suggests, the method should improve accuracy when light is falling in with a low-angle incident. I found another thing very interesting: the patent refers to smaller pixel size, i.e. you can pack more pixel on the sensor. So, given that a phase-detection AF is particularly useful on a mirrorless camera, could that indicate that Canon is working on a higher resolutions sensor (with an improved AF) for its more pro-oriented mirrorless camera that we expect to be announced later this year?

  • Patent Publication No. 2012-151215
    • 2012.8.9 Release Date
    • 2011.1.18 filing date
  • Existing techniques
    • JP 2002-314062
    • Conventional techniques beam separation is insufficient, Ranging Accuracy is poor
      • Scattering effects due to wiring
      • The smaller the angle of incidence, it is difficult to detect
      • Smaller pixel size, the value of F becomes larger microlenses (dark), they spread the light next to almost the same in the size of the image pixel size and pixel diffraction
  • And waveguide
    • The waveguide, depending on the angle of incidence of the light flux, there is a characteristic (waveguide mode) is different states of light propagation in the waveguide
  • Canon ‘s patented
    • Consisting of waveguide waveguide and vice
      • Guiding light of two different incident direction: waveguide
      • Vice waveguide: one for each waveguide comprises a waveguide two sub-
    • Can be detected by the photoelectric conversion unit specific, the incident light at a particular angle
    • Impact of wiring
      • The incident light to propagate the core portion of the waveguide, reducing the impact of wiring
    • Low-angle incident light, by using the corresponding waveguide mode depends on the incident direction
    • Small pixel size, support by limiting the distribution of the emitted light
      • Achieved by suppressing the spatial width confinement in the waveguide propagation of light sub-