EF to L-Mount Adaptor by Fotodiox
This is an alternative to the Sigma MC21 that lets you mount Canon EF lenses onto your new Lumix S-series bodies such as the S1R and S1H. The short version of this review is that they work just fine for AF lenses and represents excellent value.
Viltrox EF-L Pro - Quick Review
For extra stability and good compatibility, this EF-L adaptor plays nicely with the latest LUMIX bodies and older EF lenses.
New Life for EF Lenses
Not only does the AF system on the LUMIX S5II deliver amazing results for native L-mount lenses, but the performance of EF lenses is exceptional to the point of giving Canon owners a legitimate upgrade path at an affordable price.