I have lost the tripod mounting ring for my Canon 70-200mm f/2.8 IS USM. It is very expensive to replace it with an original one [about £140.00 as of May 2012]. I have noticed that there exist ...
What are the types of Canon's tripod mount rings? I've heard about A, B, C and D types, but have no idea what it means or what the difference between them is.