I'm having trouble getting water droplets sharp. I've made them with a mix of water and glycerin, dropped them on glass which is set over upturned table legs and have put coloured paper underneath, about 8" away. My 60d and sigma macro lens is inverted on my tripod. I'm wondering if just the little movement of the tripod, it's a flimsy but great manfrotto b free, is causing the droplets not to be sharp? I'm having trouble focusing anyway, am using manual focus and settings but struggling. Any ideas? Thanks in advance.