Canon Patent: 28-70mm f/2.8 And 28-60mm f/4 Lenses For RF Mount

And yet another Canon patent application for lenses for the RF mount (EOS R).

Canon patent application 2021-179550A (Japan, spotted by Hi Lows Note) discusses optical formulas for a 28-70mm f/2.8 and a 28-60mm f/4 lens, both for full frame mirrorless cameras (hence for the RF mount on the EOS R).

Embodiment 1

• Zoom ratio: 2.35
• Focal length (mm): 28.84 39.89 67.90
• F number: 2.91 2.91 2.91
• Half angle of view (degree): 32.65 28.06 17.67
• Image height (mm): 21.64 21.64 21.64
• Lens length (mm): 149.46 133.18 115.94
• Back focus (mm): 13.48 19.38 27.78

Embodiment 2

• Zoom ratio: 2.35
• Focal length (mm): 28.84 39.96 67.90
• F number: 2.91 2.91 2.91
• Half angle of view (degree): 32.68 27.27 17.67
• Image height (mm): 18.50 20.60 21.64
• Lens length (mm): 152.91 136.27 115.98
• Back focus (mm): 13.50 19.41 26.94

Embodiment 3

• Zoom ratio: 2.08
• Focal length (mm): 28.84 33.20 60.00
• F number: 4.12 4.12 4.12
• Half angle of view (degree): 32.68 31.82 19.83
• Image height (mm): 18.50 20.60 21.64
• Lens length (mm): 141.33 130.27 104.61
• Back focus (mm): 19.70 21.65 35.51

Embodiment 4

• Zoom ratio: 2.35
• Focal length (mm): 28.84 37.16 67.90
• F number: 2.91 2.91 2.91
• Half angle of view (degree): 32.68 29.00 17.67
• Image height (mm): 18.50 20.60 21.64
• Lens length (mm): 121.04 110.42 101.92
• Back focus (mm): 9.97 13.25 25.53

Embodiment 5

• Zoom ratio: 2.35
• Focal length (mm): 28.84 39.87 67.90
• F number: 2.91 2.91 2.91
• Half angle of view (degree): 32.65 28.07 17.67
• Image height (mm): 21.64 21.64 21.64
• Lens length (mm): 146.19 132.32 116.42
• Back focus (mm): 14.84 20.01 28.77