Compressed air,then Zeiss wipes for me.I only clean when it's really needed.The hardest thing on lenses is cleaning them.I'm also going to take Sidewinder72's advice and try the distilled water rather than the wipes.I have over a dozen Leupolds and have covers for most of them.They're the best way to clean a scope.Meaning you don't have to nearly as much.I just bought a tiny DeWalt air compressor for my gun room,and have found it to be one of those things I didn't have,but now that I have one,I don't know how I got along without it.I invested less than 300 bucks,and am very pleased with it.