Canon RF800mm F5.6 L IS USM Instructions Manual page 11

4. Setting the Focusing Distance Range
Focusing distance range selector switch
You can set the focusing distance range with a
switch. By setting a suitable focusing distance
range, the lens is prevented from focusing on a
subject at an unintended distance.
Focusing distance range
Lens
RF800mm F5.6 L IS USM
RF1200mm F8 L IS USM
Ranges
FULL (2.6m-∞)
2.6m-20m
20m-∞
FULL (4.3m-∞)
4.3m-30m
30m-∞
ENG-10