Lenses to use with the M3 Cinema lens adapter?

It's been awhile since i've posted here, but I had a question and immediately thought of you guys!

I currently have an opportunity to have a funded production, and with the money I am planning on purchasing the M3 Cinema Lens Adaper by Redrock Micro. I own an FX1 and would like to create a shallower DOF and utilize different lenses. My one problem is I do not know much about lenses and could use some guidance. I was thinking a standard 50mm lens would do?

Any input / recommendations would be great!