Got my first L and it's awesome. Very sharp and bokeh is nice.My only issue is it did not come with a tripod collar. I guess I will be picking up a knock off. My question is all the ones I see on amazon say 300mm f4l but none with the is. I see the 70-200 f4 and f4 is seem to use a different collars. so i just want to know if they are the same.