Part of the walk is seeing peripherally. And seeing peripherally is looking everywhere at once. Movement to the side often trips my sensor so I try not to mono-focus even when I've targeted something. There may be something off to the side I don't want to miss. In this instance, with my friend Tom, we were wandering in a small Czech Republic town, and I was looking to the left when I turned to investigate the front of Tom's lens that was just noticeable in my periphery. I admit I asked him to "Hold it", which he did, but the point is "Keep your eyes open!"