As a photographer I have found the past three weeks of hiking frustrating. It has not been the heat and the sweating but the fogging over of my lens and viewfinder at inopportune moments that has hampered by photographic abilities. Out of my frustration I have created humidity Photography tip, to keep lenses from foggy up in humidity wrap gear in freshly warmed towels from dryer 1/2 hr before going outside. Most of us live in the comfort of air conditioned abodes, the towels help your gear to slowly warm up and equalize to the outside temperatures. Make sure towels are warm not hot.