Mounted on a D5500. Very sharp lens, generally, but in a large room at night (New Years party), I was trying to take pics without flash, assuming it should be no problem for this rig. When I downloaded today I was shocked at how many pics missed the focus- VERY soft on many occasions. Ideas: 1) maybe aperture prioritize shooting so that DOF is larger to cover for small focus misses? 2) maybe switch to sing'e-point focusing so that my margin of error is smaller?