wetnwld wrote:
Has anyone ever worn out a lens by keeping the front element clean?
Yes, but not recently.
The glass in older lenses and the early lens coatings were "softer" than modern ones. Plus those "lens tissues" that Kodak and others used to sell us were terrible on lenses.... Paper made from wood pulp which has minerals in it that caused micro scratches that accumulated over time and became "cleaning marks". Lenses from the early 1960s, 1950s and earlier sometimes show this type of damage.
Modern lenses and their coatings are much tougher. Usually a whole lot tougher than the filters being used to protect them, in fact. Plus we have much better cleaning materials today, such as micro fiber cloths.
The OP may feel good that their filter "saved" their lens. But there's really no proof of that at all. All they really can say for certain is that they broke a filter and had to replace it. The lens might have survived the drop just fine without any filter. In fact there may be internal damage to the lens that they don't see.... damage to the focus, zoom or aperture mechanisms, de-centered elements, focus knocked out of calibration, etc.
There's very little real evidence one way or the other about the "protection" filters give to lenses. Anyone considering sinking money into protective filters for all their lenses should first view Steve's video, where he actually tests the effectiveness of protective filters:
https://www.youtube.com/watch?v=P0CLPTd6Bds I have no problem with other people putting "protective" filters on their lenses. I just think it's pretty silly and a waste of money. But that's their problem and if it makes them feel better, fine.
And, yes, I have "protective" filters for my lenses, too. They're stored separate from my lenses until and unless actually needed (like all types of filters I use). Some examples where I'd install them would be when out shooting in a sand storm or at the beach or a paint ball battle or similar. Those filters are among my least often used accessories and were pretty low priority. Somehow my lenses have survived for decades without them, including a few drops and bad bumps. I've broken some lens hoods and lens caps, but never done serious damage to a lens!
Back when I was shooting film I used UV and stronger warming filters (81A, 81B, etc.) for their actual purpose... to counteract film's tendency to go "blue" because of it's over-sensitivity to UV light. Those aren't necessary with digital cameras (if I want a warmer image, I use Warm Cards to set a custom white balance).
Even if I did do damage to the front element of a lens, that wouldn't mean the lens is "destroyed". It just means that the front element needs to be replaced (and the rest of the lens checked for proper function and re-calibrated, if necessary). That's often a fairly reasonable cost. I bet in a lot of cases it's not much more than the cost of a filter. Though, frankly, I've never had to have it done so can't say for sure and imagine it varies a lot depending upon the particular lens and it's optical design.