Archive for: DO

Patent: EF 400 f/4 DO IS II

Patent: EF 400 f/4 DO IS II

Another DO patent
We haven’t seen a new DO lens in a long time, but the patents haven’t stopped. It looks like Canon is continuing the R&D, I’d love to see it go somewhere.

Interpretation and self-description of the patent literature

  • 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

Source: [EG] | Canon EF 400 f/4 DO IS

Patent: 600 f/4 DO IS & 400 f/2.8 DO IS

Patent: 600 f/4 DO IS & 400 f/2.8 DO IS

Patent Time!
More diffractive optic patents from Canon. This time, another 600 f/4 IS DO lens and a 400 f/2.8 DO IS.

With the cost of the new super telephotos from Canon, I can’t imagine what new DO lenses would cost.

Continue reading for the patent breakdown….

Patent Publication No. 2012-88427

  • 2012.5.10 Release Date
  • 2010.10.18 filing date

Example 1

  • Focal length f = 585.00mm
  • Fno 4.12
  • Image height 21.64mm
  • Length 468.50mm lens
  • BF 90.78mm
  • 15 sheets of 9 group lens configuration
  • One aspherical surface a
  • 2 UD glass sheet
  • One fluorite
  • A plane diffraction

Example 2

  • Focal length f = 391.86mm
  • Fno 2.88
  • Image height 21.64mm
  • Length 367.51mm lens
  • BF 50.01mm
  • Lens Construction 14 elements in 9 groups sheet
  • 2 2 aspherical surface
  • 1 UD glass sheet
  • One fluorite
  • A plane diffraction
  • Group 3 consists of positive and negative positive
  • Inner Focus (group 2)
  • Strengthen the refractive power of the front lens group, and to shorten the overall length, the sensitivity is increased, it is difficult to manufacture and assembly
  • The number of lens group at the end of the super-telephoto lens is determined by the balance of the total length and chromatic aberration
  • And shorten the length and reconcile, the correction of chromatic aberration, the number will increase
  • It is important to the length of each degree
  • Weight of the first lens group, 70% to 9 on the whole
  • Canon patents is reduced to three the first group
  • Aspherical and one eye in group 1 group, field curvature correction, the distortion
  • Diffractive optical element and the second two groups in the first group, the chromatic aberration correction

Source: [EG]

Patent: New Diffractive Optic Patents

Patent: New Diffractive Optic Patents

More DO Lenses?
A few patents in regards to diffractive optics have come about. 70-300 f/4.5-5.6 DO IS, 14 f/2.8 DO and a 600 f/4 DO IS.

Diffractive optic patents keep coming up, though no new products are being announced. It does appear Canon is invested in the technology and thinks there is a market for it. I am a big fan of the 400 DO and hope to see longer DO lenses in the future.

Read more about the patents after the break.

Patent Publication No. 2012-78397

  • 2012.4.19 Release Date
  • 2010.9.30 filing date

Example 1

  • Zoom ratio 4.01
  • 135.50 – - 290.90mm 72.50 focal length
  • Fno 4.66 -. 4.97 – 5.87
  • 9.07 – - 4.25deg 16.62 a half angle of view.
  • Image height 21.64mm
  • 171.47 – - 204.08mm 144.08 full-length lens
  • BF 40.08mm
  • 18 sheets 12 group lens configuration
  • 3 UD glass sheet
  • A plane diffraction
  • Seven-group zoom positive and negative positive positive and negative polarity
  • Inner Focus (Group 6)
  • Shake correction (group 2)

Example 2

  • Zoom ratio 2.84
  • 200.00 – - 292.50mm 103.00 focal length
  • Fno 4.67 -. 5.44 – 5.77
  • 6.17 – - 4.23deg 11.86 a half angle of view.
  • Image height 21.64mm
  • 189.12 – - 210.66mm 162.16 full-length lens
  • BF 45.16 – 58.25 – 70.16mm
  • 13 pieces in 11 groups Lens Construction
  • 2 UD glass sheet
  • A plane diffraction
  • Five-group zoom of positive and negative positive positive and negative
  • Rear focus

Example 3

  • 14.36mm focal length
  • Fno. 2.89
  • 56.38deg half angle of view.
  • Image height 21.60mm
  • Length 133.66mm lens
  • BF 38.47mm
  • 16 pieces in 10 groups Lens Construction
  • 2 UD glass sheet
  • Two surface diffraction
  • Two positive lens group a negative
  • (Part of the front group) Inner Focus

Example 4

  • 584.94mm focal length
  • Fno. 4.12
  • 2.12deg half angle of view.
  • Image height 21.64mm
  • Length 404.06mm lens
  • BF 123.32mm
  • 18 sheets 12 group lens configuration
  • 3 UD glass sheet
  • One fluorite
  • Two groups of positive-positive lens
  • (Part of the front group) Inner Focus

Conventional diffractive optical element

  • Because there is a thick diffraction grating, and obliquely incident light, the diffraction efficiency is reduced
  • When the diffraction efficiency is reduced, flare, ghost, imaging performance deterioration, such as contrast degradation occurs

Canon’s patent

  • Can be in close contact with another medium to a diffraction grating, to reduce the thickness
  • Capable of suppressing a decrease in diffraction efficiency
  • With another medium, and fine particle dispersion ultraviolet curing resin material

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Canon 16-35 f/2.8 DO Patent

Canon 16-35 f/2.8 DO Patent

More lens patents
This is an interesting DO patent from Canon. There seems to be a lot of them showing up, but no new DO products in a long while.

I’ve been told the lack of an A+ filterable wide angle from Canon for a full frame camera will be addressed sooner than later. Yes, there’s Zeiss, but most want AF.

Patent Publication No. 2011-145518

  • Release Date 2011.7.28
  • Filing date 2010.1.15

Example 1

  • Focal length f = 16.48 – 24.00 – 33.95 mm
  • Fno = 2.91
  • Half angle of 52.70 – 42.04 – 32.51 °
  • 4 aspherical surfaces
  • Zoom Ratio 2.06
  • Four-group zoom lens plus a negative sign
  • Second lens focusing is performed by Inner Focus
  • Solve various problems using the diffractive optical element
  • The astigmatism of the telephoto kept in order, to increase the refractive index of the positive lens
  • A high refractive index, chromatic aberration occurs
  • Aberration and astigmatism in the center of the telephoto image has a correlation, it is difficult to simultaneously correct
  • Made achromatic diffractive optical element, a positive lens astigmatism correcting high refractive index

Source [EG]

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