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Canon Patent: RF 28-70mm f/2.8 Lens That Retracts When Zooming

Canon Patent

Rather interesting Canon patent for a 28-70mm f/2.8 lens that becomes shorter when zoomed to the telephoto end, i.e. it retracts.

Canon patent 2022147945 (Japan, published 10/6/2022) discusses a rather interesting optical formula for a retracting 28-70mm f/2.8 zoom lens for the RF mount. A pretty unique optical design.

From the patent literature:

A zoom lens is provided which is compact and lightweight and capable of achieving high optical performance over the entire zoom range and all object distances.

Example 1

  • Focal length: 28.84-67.90
  • F-value: 2.91
  • Half angle of view: 32.65-17.67
  • Image height: 18.48-21.64
  • Overall length: 149.46-115.94
  • Back focus: 13.48-27.78

Example 2

  • Focal length: 24.72-67.90
  • F-value: 2.91
  • Half angle of view: 35.02-17.67
  • Image height: 17.32-21.64
  • Overall length: 150.00-130.39
  • Back focus: 9.87-27.17

Example 3

  • Focal length: 28.84-67.90
  • F-value: 2.91
  • Half angle of view: 34.77-17.67
  • Image height: 20.02-21.64
  • Overall length: 152.61-120.01
  • Back focus: 22.71-41.28

More Canon patent applications are listed here. Some particularly interesting patent applications we think might get into production are these:

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