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Canon Patent: RF 70mm F1.8 STM Lens For EOS R System

Canon Patent
Drawing from the patent literature

A new Thursday, a new Canon patent. Not surprising yet another one for the RF mount. The whole thing was spotted by asobinet.com.

Canon patent application 2021-131499 (Japan) discusses optical formulas for what appears to be an RF 70mm f/1.8 STM lens for Canon’s full frame mirrorless system EOS R. From the patent literature:

PROBLEM TO BE SOLVED

To provide a compact, lightweight and large-diameter optical system.

Patent Document 1 describes a double-Gauss type optical system capable of correcting various aberrations with a small number of lenses

However, the double-Gauss type optical system as disclosed in Patent Document 1 satisfactorily corrects various aberrations such as spherical aberration and curvature of field when the symmetry is broken due to miniaturization. Becomes difficult. In particular, when the optical system has a large aperture ratio, it becomes difficult to suppress sagittal flare and coma flare at an intermediate angle of view.

Therefore, an object of the present invention is to provide an optical system and an image pickup apparatus having high optical performance while being compact and having a large aperture ratio.

Embodiment 1:

  • Focal length 49.57
  • F number 1.85
  • Half angle of view 23.58
  • Image height 21.64
  • Lens overall length 59.59
  • BF 25.67

Embodiment 2:

  • Focal length 70.00
  • F number 1.85
  • Half angle of view 17.17
  • Image height 21.64
  • Lens overall length 83.52
  • BF 36.62

According to asobinet, the lens discussed in the patent literature has an optical design similar to the RF 50mm F1.8 STM. Maybe it is another excellent performer at an affordable price.

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

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