Hi,the filter kit (SKU.1877) has adapter rings(67mm/72mm/77mm/82mm) and separate 49mm/52mm/55mm/58mm/62mm adapter rings to sell,it can fit if your lens size is included. 

Since the Olympus e520 is a Four Thirds sensor this adapter will NOT work with it. It is made for Micro 4/3 sensors, not 4/3. 

No, this is just for the mirrorless canons 

your lens curvature will require an adapter for any filter system. I saw the Lee filter adapter for this lens...but it seems it does not fit all filter holders. Lee filters will work with the adapter. 

The benefit of this adapter is that it’s suitable for Pentax DA lenses that don’t have an aperture ring. The silver ring on the adapter controls the aperture linkage on the back of the lens. Although a lens might typically have a aperture range of f2.8 to f22, the adapter only has 5 stops, and the real value of the aperture is guesswork, however a mft camera will have no trouble gaining the correct exposure. Lenses with their own aperture ring can still be used on this adapter, you just need to see the adapter to ‘open’.