Such a Nice Lens
This lens gets less credit than it deserves based on the reviews. Very optimal focal range for landscape photography, especially backpacking. I'll take the extra 4 degree maximum angle of view over the 17-55 off-brands extra 5 mm on the long end--way better for landscape photography needs. The lens build is so nice--needs to be if it's going to be your primary shooting lens. I love how the focus ring spins freely when you go beyond the upper and lower limits. The lens is sharp enough for what I do. The color is very rich, probably a little richer than my 12-24 especially beyond 18mm.
CA can be a problem but mostly at closer subject to Photographer distances. Not to sharp below f4.