I have recently purchased a UE40C7000 3DTV. When the 3D function works, it's fantastic. However, it often appears dark and blurred - particularly objects or people in the background of the picture. Sometimes (but not always) the problem clears after a while. I've tried changing multiple settings, but to no avail. I've also tried turning off the wall lights near the TV, in case they were interfering with the glasses. The manual seems to say it can take 'a while' for 3D to warm up, but I'm guessing half an hour is beyond the anticipated timescales!
Thanks in advance for your help