A new Canon patent application spotted by asobinet.com that discusses optical formulas for a RF 28-70mm f/2.8L lens. The Canon RF Lens is a RF 28-70mm f/2.8L with inner focusing and that does not extend might be in the works.
The lens is indeed described to be shorter at the telephoto end (emphasis mine) in both embodiment:
- Wide-angle intermediate telephoto
- Focal length 28.84 36.81 67.90
- F number 2.91 2.91 2.91
- Half angle of view (°) 32.68 29.23 17.67
- Image height 18.50 20.60 21.64
- Lens total length 117.09 109.31 101.58
- BF 9.99 13.47 21.59
- Focal length 28.84 37.17 67.90
- F number 2.91 2.91 2.91
- Half angle of view (°) 32.65 28.90 17.67
- Image height 21.64 21.64 21.64
- Lens total length 132.62 122.81 111.18
- BF 21.92 26.79 39.84