Bill_Green
Member
Like everyone else I did the testing and determined that UV filters degrade image quality, and in the case of Canons AF accuracy and reliability as well, and only use UV filters when things are flying at my front element. However, it appears that Canon lenses need the filter for sealing.
This past week we were shooting video with a 7D and 17-40L, including two close car to car shots on a dirt road - one with the camera attached to the front of the video car with a suction cup, the other with the photographer holding the camera and shooting out the back of the lead car. After those two shots, totaling at most three minutes, with vehicle speeds at 25 mph, the INSIDE lens elements were completely caked with dust. Not a little dust, totally covered. I would say that the lens was exposed to about as much dust as getting caught on the prairie on a windy day.
This is the second time the lens is going back to Canon for disassembly and cleaning after shooting in a dusty environment. However, to put the level of dust in perspective, we shot with three cameras, changing lenses on all of them every few minutes and never got a spec of sensor dust on any camera.
All I can surmise is that the lens needs a filter on the front to seal it as it looks to have some space between the plastic on the front and the outside of the lens barrel. However, when we noticed the dust was after the shot with the photographer hanging out the back of the lead vehicle. In that shot, the dust was moving straight up from the road, hitting the lens perpendicular to the barrel.
As much as Canon touts their weather sealing and quality of their L lens construction, this was a bit of a surprise. I don't have any specific recommendations since I don't know exactly how the dust entered the lens, but consider yourselves warned.
On a side note, this was my first exposure to the 7D. I never shot with it, but was extremely impressed by it.
This past week we were shooting video with a 7D and 17-40L, including two close car to car shots on a dirt road - one with the camera attached to the front of the video car with a suction cup, the other with the photographer holding the camera and shooting out the back of the lead car. After those two shots, totaling at most three minutes, with vehicle speeds at 25 mph, the INSIDE lens elements were completely caked with dust. Not a little dust, totally covered. I would say that the lens was exposed to about as much dust as getting caught on the prairie on a windy day.
This is the second time the lens is going back to Canon for disassembly and cleaning after shooting in a dusty environment. However, to put the level of dust in perspective, we shot with three cameras, changing lenses on all of them every few minutes and never got a spec of sensor dust on any camera.
All I can surmise is that the lens needs a filter on the front to seal it as it looks to have some space between the plastic on the front and the outside of the lens barrel. However, when we noticed the dust was after the shot with the photographer hanging out the back of the lead vehicle. In that shot, the dust was moving straight up from the road, hitting the lens perpendicular to the barrel.
As much as Canon touts their weather sealing and quality of their L lens construction, this was a bit of a surprise. I don't have any specific recommendations since I don't know exactly how the dust entered the lens, but consider yourselves warned.
On a side note, this was my first exposure to the 7D. I never shot with it, but was extremely impressed by it.