Canon continues to work on focal length reducers.

What's a focal length reducer you ask?

It's an adapter that reduces the focal length of a lens and at the same time increases the maximum aperture, basically the opposite of teleconverters.

Canon has yet to release such a product, but we suspect this type of converter could benefit the EOS M system as well as an upcoming APS-C EOS R body.

Below are a bunch of focal length reduced optical formulas from Japan patent JP-A-2019-003074

Specification and lens arrangement of master lens 1 (18-55mm, F2.8)

  • Zoom ratio: 3.05
  • Focal length: 17.50 – 53.3 mm
  • F number: 2.80 – 2.80
  • Half angle of view: 36.65 – 13.71
  • Image height: 13.02 – 13.02mm
  • Lens length: 148.81 – 172.70mm
  • Back focus: 35.51 – 40.31mm

Specification and lens arrangement of master lens 1 with reducer 1

  • Focal length: 11.36mm
  • F number: 1.82
  • Half angle of view: 36.67
  • Image height: 8.46mm
  • Lens length: 142.26mm
  • Back focus: 2.00mm

Specification and lens arrangement of master lens 2 (34mm, F1.4)

  • Focal length: 34.20mm
  • F number: 1.45
  • Half angle of view: 32.32
  • Image height: 21.64mm
  • Lens length: 129.16mm
  • Back focus: 39.35mm

Specification and lens arrangement of master lens 2 with reducer 5

  • Focal length: 23.92mm
  • F number: 1.02
  • Half angle of view: 32.33
  • Image height: 15.14mm
  • Lens length: 125.59mm
  • Back focus: 2.00mm

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