I'm considering buying my first spotting scope. Intended use would be for backpack/backcountry hunting. I'm debating whether to go with the 60-65 mm size range or 80-85 mm size range. I'm kind of an ounce counter, but don't want to pack the lighter scope if it won't be useful. For the sake of this thread, let's assume I need more than a pair of 15x56 binos.