At f/1.2, the depth of field on an 85mm lens is approximately 2.5 centimeters at typical portrait distance. That is the width of a human eye. Focus must land on the near eye, precisely, every frame. The reason to own an RF 85mm f/1.2L DS is the RF 85mm f/1.2L DS — and the reason it is usable wide open is Eye AF on the R5 Mark II or R6 Mark II.