The 100-400mm II has severe focus breathing, the effective focal length dropping from 400mm to 178mm at its minimum focal distance of 970mm.
Prompted by someone asking if there is focus breathing with the RF 100-500mm, I have calculated the focal length at the mfd from data reported in The-digital-photo site:
Specified Min Focus Distance 35.43” (900mm)
Tested Min Focus Distance (Wide / Long) 38.23” / 47.01” (971mm / 1194mm)
Maximum Magnification (MM) 0.33x
Combining them gives a maximum focal length of 224mm at the minimum focal distance of 1194mm.
Prompted by someone asking if there is focus breathing with the RF 100-500mm, I have calculated the focal length at the mfd from data reported in The-digital-photo site:
Specified Min Focus Distance 35.43” (900mm)
Tested Min Focus Distance (Wide / Long) 38.23” / 47.01” (971mm / 1194mm)
Maximum Magnification (MM) 0.33x
Combining them gives a maximum focal length of 224mm at the minimum focal distance of 1194mm.