Aguinaldo , I really enjoy the colors you get
Regarding focus with a fast wide angle, I have run into similar situations with my 20mm f1.8 AFS, I tried focus-recompose and then discover the image is not in focus ... It was surprising for me to find out the 20mm lens wouldn't have enough DOF to cover any movement I may have done when recomposing, since missing a few images due to bad focus, I'm now more careful