"A filter is infinitely better for protection if you dont already use one"
maybe for around town or in a studio but not if you are cutting your way through bush and spend a lot of time hiking off trails... so many things would hit my filter like branches, rock faces and tree trunks that I would be replacing the filter every week. I've dropped my camera multiple times with the 100-400 on it.. slipped and fell with the camera taking a hit lens first several times... bashed it against all sorts of objects including rock faces... with a filter I would have gone through multiple ones and maybe even damaged the lens front.. I have yet to have my lens be damaged with the hood on it... well except for the time it fell off a waterfall
Canon 7D + 50D + EF 100-400mm f/4.5-5.6L IS USM + EF 24-105mm f/4L IS USM + EF 100mm f/2.8L Macro IS USM
Pelican // Black Rapid // Think Tank // Manfrotto // Garmin
Reflections On Canadian Wildlife