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Thursday, June 13, 2013

New Canon Patents - 100-400mm and 70-300mm

Canon has patented two new lens design - 100-400mm f/4.5-5.6 and 70-300mm f/4.5-5.6. The current model of these lens are two of my favorite in the 'L' lens lineup. You can read my review here. I would not read too much into these new patent filings. Canon routinely file thousand of patents a year and I expect the EF 100-400mm replacement to be a little faster on the short end. You can read my latest post on this excellent lens here. The Egami article in Japanese, on the new patents is here.

Patent Publication No. 2013-105053 (machine translated)

  • Publication date 2013.5.30
  • Filing date 2011.11.15

Example 1

  • Zoom ratio 4.01
  • Focal length f = 72.48-135.49-290.86mm
  • Fno. 4.58-4.94-5.85
  • Half angle ω = 16.62-9.07-4.25 °
  • Image height Y = 21.64mm
  • 143.42-175.48-201.87mm overall length of the lens
  • BF 39.98mm

Example 3

  • Zoom ratio 3.75
  • Focal length f = 104.16-166.66-391.00mm
  • Fno. 4.60-5.20-5.80
  • Half angle ω = 11.73-7.40-3.17 °
  • Image height Y = 21.64mm
  • 221.48-252.31-300.68mm overall length of the lens
  • BF 70.65-87.69-113.37mm

Canon Patent

  • I want to put in the first group the anomalous dispersion optical element
  • It is possible correction and lateral chromatic axial chromatic aberration, but spherical aberration of color and field curvature occurs
  • By optimizing the placement, the correction and field curvature, the spherical aberration of the color of g-line

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