wow.

.what an interesting shot..very moody...Not sure about the focus problem..did ya try auto focus??not sure how good the 350 focusses in low light on auto....could try a sort of bracketing techniquue, where you take a shot and check the focus, then slightly change the focus and take another shot (time exp of course) untill you get it right..That would be one way i spose..or you could try shining alight on the object to focus and then turn it off for the shot...your shot looked like it had a light source hitting the tree anyway??Sorry im not a great help, but someone in this forum im sure will sort you out...cheers
again...well done...great shot