Yesterday I got home and grabbed my camera and headed back out to take some storm shots. I raced to a nearby high point overlooking the valley and started taking photos. It was starting to sprinkle and even though there was a hood on my lens a drop of water landed on it. Since I hadn't taken the time to grab my camera bag I wiped it with my shirt and it created a smear. So that ended my shooting. I went home and got my lens cleaning tissues out but whatever was there was stubborn. It finally came off but it got me to wondering. What is the best lens cleaning liquid to more easily remove these kinds of stubborn smears without damaging an lens coating?