I don't see how a filter is protecting anything from impact; that thing is so thin, you can practically push your thumb through it - unlike the front element, which is a very thick piece of glass and requires an immense amount of force to crack. The fact that both the lens cap and front element are undamaged while the filter is completely shattered goes to show just how fragile and useless the filter was as a means of protection. If anything, the lens cap was the real hero in this case, not the filter. Obviously, there are situations when a filter can be useful for protection, such as shooting in a sand storm. However, it doesn't really protect from violent knocks to the lens. Caps and hoods do a far superior job.