Here is a Philip Bloom Meet Up in Key West where they spent the day shooting Anamorphic, with an anamorphic clamp. I don't think this video looks that great, but Im not sure if its the clamp or the lenses they used in the clamp.
The Anamorphic Clamp available for $75 USD at vid-atlantic.com/anamorphic
I guess what the clamp allows you to do is mount anamorphic lenses to the 5D and lock in proper horizontal and vertical alignment.
Want to master Microsoft Excel and take your work-from-home job prospects to the next level? Jump-start your career with our Premium A-to-Z Microsoft Excel Training Bundle from the new Gadget Hacks Shop and get lifetime access to more than 40 hours of Basic to Advanced instruction on functions, formula, tools, and more.