I share my experience with you. I went to botanical garden and was taking a picture of some leaves above my head. I looked up and was looking into the viewfinder when suddenly a bird dropped its poo on me. Really like bulls eye. the poo (white, thick but still watery, and still got some insects legs in it )hit my front lens and into the viewfinder and into the gap of the zoom lens. I did not even had a tissue with me. from this on, I always have tissue paper, lens cloth, cleaning pen (double sided. one side brush. the other side cleaner) and cotton buds. they are not that heavy/bulky.