i just bought the R2A. i agree in dim light focusing can be a bit tricky. especially if theres no sharp edges to assist - e.g. if u are photographhying people. what i did , was as what people advised, is just try and set the depth of field a bit deeper, and manually adjust the lens based on what i thought was the range to subject.
personally, im not concerned if the pictures dont come out tack sharp.
personally, im not concerned if the pictures dont come out tack sharp.