Without a doubt, it is a lens that is famous for having an excellent dof. I like to play with different settings for different effects, am forgetful and takes a pic or two to remember to change the f.stop or distance.
Like here was trying to play with softening the background. Then start swimming, forget the old settings. Just have to flip camera over to check. Seeing all info in the viewfinder spoils you.
It helps, but nothing is foolproof. You just have to take your time, set the shot more. For instance, you have to take your eye out of the viewfinder and look at the lens itself to check the f.stop. No more lifting the camera and firing away.