cjones,on your helix si ,if the brushpile is old,small limbs,not in water colum and if hard bottom ,it will not show you those limbs,yours or theres.what you have to do to help you on older brush is to train your eyes and the best way to do this is to find a good pile and put a marker on it ,then go over it just far enough that it will not be in water column,stop unit by hitting cursor,then adjust it as good as you can,after that look at it until you know what you are seeing,it will usually be a light spot with a little shadow behind it.do not range out too far and for practice ,just use one side to give you a bigger pic.go by it at different angles and see how well you can pick it up with unit and with your eyes.All of us have a tendercy to think of our units as greater than they are,we see fish and brush that just jumps out on the screen but fail to take into account all those times that we miss seeing piles that we pass by.practice is going to be your greatest friend,and being alone is the best way unless you have someone more knowledgeable than you going with you