Got me a beast of a lens.. didnt get the 9-11400$ ones in a shutter..

How does one figure out what size shutter is needed, or if its POSSIBLE to get a shutter big enough for the beast? THe 4 screw metal mounting ring is stamped 50mm.

I have to admit its a beautiful lens, crisp just holding it up to the eyeball. Its odd to see a lens with a double scale showing f stop and size of opening in MM.