Mervyn, I use both a Nikon D800 and a Fuji XE-2. Apart from size, I find accuracy of auto focus
one of the greatest advantages of Fuji. It should be even better on an XT1. In my experience, focus accuracy with static
objects is more precise and consistent with the Fuji. For things that are
moving, though, the Nikon autofocus is much better. But from what I have read, the new autofocus systems on the XT1
and XT10 are a
lot better than my XE2 for things that are moving.
Three thoughts about possible issues. First, Fuji autofocus seems much better in the S mode than the C mode. I
sometimes knock the dial into C mode by accident. Second, the size of the
adjustable autofocus area zone matters a lot. With a big zone, my camera sometimes focuses on foreground or
background objects. So I
always keeps the zone very tight, which works fine with static objects. Finally, I sometimes get out of focus shots when I
try to focus on
low contrast areas, especially in low light. In these cases, I either try to include some sort of high contrast edge in the
focus area, or
switch to manual focus mode which is surprisingly easy on the Fuji body.