Air gets rid of lose particles. A delicate touch with a soft brush gets rid of other loose particles. Those kits the eye doctor sells for glasses work well. I carry a Leupold Lens Pen in my pack and it works ok. On a couple occasions I have some how ended up with a glob of mud on a lens when on an ATV. It was so bad one time I pulled the scope and washed it in a creek. Talley or Warne QD rings can be handy.
I have probably used rain water or water from a water bottle and a cotton handkerchief more then any thing. I really don't worry to much about a dirty scope lens in the field, as long as I can see the moose and have a good aiming point I'm ok.
