The hood guards the front part of the lens against
rain, snow, dust and stray light which may cause
flare and ghost images.
Attaching the hood
On the EF 135mm f/2L USM and EF 200mm
f/2.8L II USM lenses (bayonet type)
Align the hood's bayonet flange with the
bayonet flange on the front of the lens, then
turn the hood in the direction of the arrow.
The hood can also be attached in reverse
before the lens is stored in a case.
EF 300mm f/4L USM, and EF 400mm f/5.6L USM
lenses (pull-out type)
Pull out the hood all the way, then turn it in the
direction of the arrow.