Just to let folks know that an expensive adapter does not always warranty you a perfect result. On the Voigtlander adapter, there is a light rubber gasket which protrudes into the light path too much and causing corner vignettings when shoot wide open. I removed the inner ring and repainted the inside of the adapter where the rubber ring was residing with matte paint to eliminate the problem. Thus, do not give up on your adapter whether it is expensive or cheap too quickly. There might be a solution to the problem you are experiencing.