I was wondering if anybody has any knowledge on the tripod collar on the 300mm f/2.8L IS II USM. I have an application where the collar needs to be removed to mount the lens in a rig. With other lenses this seems to be a fairly straightforward process, but I am unable to figure it out on this lens.
For the EF 300mm f/2.8L IS removing the tripod collar was fairly straightforward: Loosen the tension knob and rotate until the red dot on the collar lines up with the red dot on the lens barrel and pull the collar straight back. This lined up the four slots on the collar with the four lugs on the lens barrel.
The new EF 300mm f/2.8L IS II has a non-removable collar. The foot, however, is detachable from the rest of the collar. Unfortunately, Canon advises it requires special fastening and, as a safety precaution, recommends it only be re-attached by a Canon Service Center.
I found this: "The 300f/4 IS collar is removable, but it does not open like the 70-200 collar. Remove the lens from the camera body and put the rear lens cap in place. Then back the collar screw fully out. Finally, rotate the collar around the lens while gently exerting pressure toward the rear of the lens. At one point, and one point only, the collar will slip off the lens. Installation is the reverse."
And this: "Yes the 300 f4 IS tripod ring TMR-B(W), is removable, dismount the lens, loosen the locking screw and rotate until the TMA's red dot and the lens mount red dot are aligned and it will slip off. Refitting is the reverse of removal."
I hope that works for you.