Canon recently has filed a new lens patent in Japan. This patent is for 400mm f/4 DO lens, 600mm f/4 DO lens, and 800mm f/5.6 lens. The patent didn’t mention whether this lens is EF mount or RF mount, but hi-lows-note said these lenses could be RF mount, and upcoming EOS R could have IBIS.
Focal distance 582.00
F number 4.12
Half field angle (degree) 2.13
Image height 21.64
Whole length of the lens 394.25
BF 62.79
Focal distance 405.00
F number 4.12
Half field angle (degree) 3.06
Image height 21.64
Whole length of the lens 330.16
BF 50.46
Focal distance 795.00
F number 5.60
Half field angle (degree) 1.56
Image height 21.64
Whole length of the lens 490.24
BF 105.13