Yes, one lesson is don't bump rocks. But the other lesson is what I was getting at: people tend to be more careless when they think a filter is "protecting" their lens. Here's how I look at it. If you had been using the lens cap, or even just the lens hood, nothing would have been broken at all. If it was a 77mm B+W mrc filter you hit, not only would you be VERY lucky it didn't scratch the lens, but you are certainly out $77 (plus shipping) for the filter. That's still a pretty big hit. This is why I just use the lens cap and don't mess with flimsy filters.