The filter thread size of Olympus Zuiko Digital ED 50-200mm f2.8-3.5 SWD is 67mm.
Below are links to the filters that we recommend you to consider for your Olympus ED 50-200mm f2.8-3.5 SWD:
Read our detailed Olympus Zuiko Digital ED 50-200mm f2.8-3.5 SWD Review