Hi I was looking around for FE adapters that do actually work. I came across a similar product at www.opteka.com. The one in the photo is under the video camera adapter section but i'm sure it'll work as long as the thread size is right. It's really big and heavy.. and not to mention, costly too but for the build and quality, it's worth the money!
the really good ones for video imaging will be really expensive, and i think schneider optics make some really expensive ones. not sure if the filter sizes will fit.
but . in any case, might as well get a fe lens lor. apart from fisheye zoom lenses, there are some manual focusing ones in market as well.