Patent: Canon 17-40 f/2.8-4L

Patent: Canon 17-40 f/2.8-4L

Canon EF 17-40 f/2.8-4L Patent
Below is a patent for a new Canon wide angle zoom concept. The variable aperture is interested, if it remained as light and compact as the current 17-40 f/4L, the additional stop of light wide open would be a nice feature.

Patent Publication No. 2010-42792

  • 2012.3.1 Release Date
  • 2010.8.20 filing date

Example 1

  • 39.05mm – f = 17.64 focal length
  • Fno = 2.64 – 4.10
  • 28.99 deg – 50.80 half angle of view.
  • Image height 21.64mm
  • 136.70mm – 134.67 full-length lens
  • BF 39.97 – 64.95mm
  • Lens Construction 12 elements in 9 groups sheet
  • 4 aspherical surface

Canon’s patent

  • Negative lead type zoom lens of negative-positive
  • Small and light lens for focusing
  • Inner focus
  • Focusing the use (1b in the figure) part of the first lens group
  • Video support

Source: [EG]

cr

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