You do not bother me and thank you for helping me. I am not using any object but taking plain outdoor and landscape pictures to compare . There was no snow on the area but the sea was greyish. Maybe I should take a grey card. The 5D3 is the first...
It is underexposed on the histogram on the camera so I added 0.7 to obtain a correct picture. I used an 24-70 L II f2.8. I had the same results with the 24-105L. Never been a problem with my 5D2.