For the Olympus E-1, there is now also a set of adapters for various SLR lenses - so there are now two digital options for classic lenses like the Leica R or Contax MM line. The Olympus version is even more robustly and generously designed than the EOS version, since the Olympus system has a significantly shallower flange focal distance and therefore more space remains for adapters. As a result, the adapter for the Olympus system can remain directly on the camera (with the EOS adapter it's better to keep it on the lens). Particularly interesting for people who are simply looking for a digital option for their lenses and don't want to invest in the Olympus system. Here's the original article.