I have never understood the logic of putting a $45 piece of glass in front of a $600 lens ?
As I said before, I use Hoya HD Protectors frequently because I much prefer getting crap on a filter instead of the lens to begin with. I shoot in some harsh (for cameras, anyway) environments and I'd much rather have "a $45 piece of glass" taking the heat. The filter is removable so I can swap it out in the field if it gets caked (which it frequently does) with, say nasty a$$ salt-water residue from shooting surfers for just one example. It also cleans up very conveniently at the kitchen sink (or beach shower) without so much as touching my $1,000 lens because yeah... Cleaning that abrasive salt residue is
definitely something I want to be wiping off my front lens-element... Over and over and over again. Some photographers have the luxury of shooting in safe, "sterile" environments but that's not me.