Karin Nelson

Yeah, we’ve heard it all before. We don’t need any filters on our lenses. Filters distort. Filters are useless. Lens glass is protected by all kinds of cool coatings that make them resistant to scratches, easy to clean, bla bla bla. But the lens glass is just that, GLASS. If something hits it, it will break. No doubt about it. 
Last summer, on a kayak trip, I had my camera gear in a dry bag. The camera with a lens mounted, and my 70-300 VR, both wrapped up in towels. Somehow when unloading the stuff from the wobbly kayak, something must have gone wrong. I only noticed much later, when trying to take the lens cap off the 70-300. It was pushed in, hard to take off. And there was a crunching noise. “Crunching noise” and glass… no good.
And then the shocker: there were bits of glass everywhere. The glass… completely shattered. Somehow the padding inside the bag must have shifted, and a corner of camera body pushed against the lens, and pulverized the glass. I was close to tears… until I realized that there still was the polarizer mounted on the lens. I unscrewed it carefully… and the glass underneath it was fine.
The lens cap alone didn’t help. The force literally displaced the cap and disintegrated the (double glass) filter. But since the filter took the brunt of the impact, the lens was fine. I couldn’t believe my luck.

So in case you still believe a filter is useless, think again. I much rather replace a broken filter than a broken lens.