The problem is with camera raw. Adobe updates their raw processor according to what cameras existed at the time their software was written. So obviously the 5D3 did not exist when the raw engine for LR3.6 came out. By the time the 5D3 came to market, LR had gone to a newer version and previous ones do not get the new raw engines. So, you either buy a newer version of LR, or use the DNG converter. I would go with option 1. LR5 does indeed support the 5D3 and also has a newer, better processing engine that 3.6. I use a pair of 5D3 cameras in my wedding photography business and used to use PS CS5 and quickly upgraded to CS6. The better raw conversion was worth it. I’ve stuck with CS6 over the cloud though as it still meets my needs. Enjoy the camera and the updated software. You will be amazed at the difference of the better camera along with the processing engine.