Canon EOS 5Ds Instruction Manual page 120

3 Customizing AF FunctionsN
23: One Shot
Lens electronic MF
With the following USM and STM lenses equipped with an electronic
manual focusing function, you can set whether to use electronic manual
focusing.
EF50mm f/1.0L USM
EF85mm f/1.2L USM
EF85mm f/1.2L II USM
EF200mm f/1.8L USM
EF40mm f/2.8 STM
* As of March 2015
OFF: Disable in AF mode
When the lens's focus mode switch is set to <AF>, manual focusing
is disabled.
120
EF300mm f/2.8L USM
EF400mm f/2.8L USM
EF400mm f/2.8L II USM
EF500mm f/4.5L USM
EF24-105mm f/3.5-5.6 IS STM
: Enable after One-Shot AF
After AF operates, if you keep
pressing the shutter button halfway,
you can adjust the focus manually.
: Disable after One-Shot AF
After AF operates, manual focusing
adjustment is disabled.
EF600mm f/4L USM
EF1200mm f/5.6L USM
EF28-80mm f/2.8-4L USM