I would like to shoot small dogs at a park. I would like to hold the camera at about knee level without looking through the viewfinder and without live view. I point the camera in the general direction of the dogs when they are relatively still. If possible I would like to blur the background so am guessing I would like to use aperture prioeity at about F3.5. I am using an 1.8 lens. What is the best way to set the exposure, and focusing modes to get good results?