is anyone shooting A7r with Sony 10-18 in full frame mode? I hear it is good between 12 to 16mm, but is it really? I have been trying to use my A7r with Canon 10-18EFS and it is the best at around 14mm, but even there there is heavy vignetting at the corners which is difficult to deal with in post. Is 12 to 16 so good to almost completely lose vignetting at the corners? I am thinking about returning the 10-18 Canon and getting the 10-18 Sony then. Not interested in dropping $1300 on 16-35, I rarely shoot ultra wide, but like to have an inexpensive option