You can take a look at canon 50mm ltm lenses. The 50 1.8 is compact and has lots of great reviews and has a built in filter ring. If you want collapsible the 50 3.5 from canon is also nice and has a filter ring as well. Both lenses are quite common and affordable too. I have used both in the past before and they are good performers. I think the easiest And cheapest option is to use a series 6 adapter and get the drop in filters tons are out there.