I've been on the B&H waiting list for a year now for this little doohickey. Since then, I've taken delivery of a camera (5DIII) that was 8 months shy of being announced. Does anyone actually have a tripod collar for a 70-300L, or am I looking for a unicorn ? It looks like Canon will start delivery of the 1Dx before they release a freakin' tripod collar.