Devil's Ivy -- NEX-5 & 8mm Relfex Zoom 9-28mm f1.1 Movie Lens Front Element.
I think that once in a while, a weird and unusual lens can be a lot of fun. Of course it does not have to be expensive. In fact, the cheaper it is, the more you will enjoy using it, as you don't have to pay through the nose to get one. A cheap commercial soft focus lens can be found for around $20 on eBay, is the Sima 100mm f2. I wrote about it here and here. The Sima has a T-Mount so it should fit pretty much any cameras with the right adapter. You can also buy a rather expensive soft focus lens, like the Canon SF 135mm f2.8, Nikon 105mm or 135mm f2 DC, a Pentax 85mm f2.8, and many others, or, make your own! It's a lot easier than you think. All you really need is a piece of glass from the front element of any lens (50mm or less is good. Any longer you will need tubes), and a focusing helicoid. In fact, you can take a non-working 50mm lens and remove the rear elements and get an instant soft focus lens! Nothing can be easier. Try it!