Just got back from Arizona. Was a mule deer hunt in Unit 10. Open country, hours of time in the glass. I run Zeiss 10x50 in my Marsupials and 15x56 on the tripod. I spotted some good bucks from 200 yards to 1.6 miles away. At 1.6 miles, even at 730 am the heat waves and morning thermals made it impossible to count points. My buddy had the Swaro BTX set up. Actually made things worse. More power, more thermal interference. Get some 15's and get a good glassing chair or pad. They will do everything you need them to do. 30x magnification is good, but not in windy or desert sunrise conditions. It was 34 degrees, but with the morning sun heating up the dirt, spotter style magnification was worthless.