I'm not familiar with that model (I assume it's not a color display) but what I generally do is turn the sensitivity up until the screen in mostly black and then turn it back down until you're comfortable looking at the display. Don't turn it down so far that there are no specks here and there. I'd say you've got it about right in the pic. You may have to up the sensitivity in deeper water. All that said, lots of folks just set the newer units on auto and let it ride.