Canon 60d + Nikkor lens issue

[Crow]

Hi - I'm new to the forum and signed up as I'm hoping that someone with more expertise than myself might be able to help. I recently purchased a Nikkor 50mm f/1.8 pancake lens to use with my Canon 60d and I am experiencing a strange issue with it. In manual mode, with the settings identical (ISO, shutter speed, aperture) I get two different results when I switch between live view and the viewfinder. At f/4 the results are very similar, but at f/1.8 my viewfinder results are a stop or two darker than my live view image and at f/5.6 my live view image is darker than my viewfinder result. In other words, f/4 seems to be a crossover point which gives the most accurate result using both modes. I have tried enabling and disabling exposure compensation and I get the same result. I have also played with the lighting optimization but the result is also the same. I am using an adapter without a chip. If anyone can shed some light on this it would be much appreciated.