Canon EF300mm f/2.8L IS II USM Instructions Manual page 17

12. Case
Put the lens away as follows.
Reverse the lens hood, slip it over the lens,
and attach the lens cap.
Position the tripod mount towards you as
shown and place it in the case.
Place so that the hood's lock knob rests in
the slot near you.
Slot
Keyhole
The illustration shows the EF400mm f/2.8L IS II USM.
Lid
Strap
Lever
Fold the strap and fit it into the space near
the case hinges.
Fasten the lens securely with the strap.
Close the lid, and then push the lever while
holding the lid from above to lock.
Do not sit on top of the lens case.
O O
Place the lens in the position intended for it.
O O
Hinge
ENG-16