This is what I realized, occasionally, the focusing of my Sigma 30mm F1.4 fails me. Especially under low-light environment, it is slow and inaccurate. Well it's not terribly slow and inaccurate, but it does happen at times. It isn't front/back focusing, i tested it with the focusing chart. For other times the focusing isn't failing me, the images are crystal sharp, very sharp.
So I wonder do you guys have similar problems, or it's just me?
I have thought about switch it to 85mm 1.8, cause I am still struggling with the FL decision. I am not completely sure if i need the width of the 30mm.
is 85mm 1.8 USM focusing way faster and more accurate?
(EDIT: under enough ambient light, it doesn't struggle much)