I use this filter on the 50mm f / 1.8, to protect the front lens from scratches, mainly to avoid fingerprints. Indeed, the focus of this objective ring is beveled and adjoins the lens, so often we touch the lens when focusing manually. So, with this filter, the ring becomes more accessible and finished the prints! I do not know if the cannon products are really better price / quality than some other brands, but it is certain the compatibility of accessories: sunshield, plugs'