There are a number of after market lenses available,that will screw right into the 30.5 thread, there are also ring adapters to kick up the 30.5 to a larger size lens fit. When I do this sort of thing I use over size Wide angle lenses so that I use more of the center of the lens than the edge, make sure you don't crop your pix view and or interfer with any external meters or buttons or whatever. I also use a square lens shade that's even larger, to catch any of that nasty unwanted side light. Buy the way most good camera shops have the stuff you seeeeeek!
Well that's it...back to my KFC.