Canon EOS 6D Instruction Manual page 41

Attaching a Lens Hood
A lens hood can block unwanted light and protect the front of the lens
from rain, snow, dust, etc. Before storing the lens in a bag, etc., you can
attach the hood in reverse.
If the Lens Hood and Lens Have a Mount Index
If Neither the Lens Hood Nor the Lens Have a Mount Index
If the lens has a mount index and you do not attach the hood properly, it

may obstruct the image's periphery, making it look dark.
When attaching or detaching the hood, grasp the base of the hood when

turning it. Grasping the hood's edges when turning it may deform the
hood, resulting in failure to turn.
Align the red dots on the hood
1
and lens edges, and turn the
hood as shown by the arrow.
Turn the hood as shown in the
2
illustration.
Turn the hood clockwise until it

attaches securely.
Attach the hood.
Turn the hood as shown by the arrow

until it attaches securely.
Attaching and Detaching a Lens
41