“Some might suggest that, hey, you can always remove the filter if and when IQ is a concern. That's true. But, yeah, like I'm gonna stop shooting thinking, "Hey, this is going to be one of my best shots ever and I really want to make sure it's perfect.... I'd better remove that protection filter".
Let's see here. You are smart enough to know what camera you want to use. And smart enough to know what lens to put on it. Even smart enough to know what settings are going to work. I guess you know where you are going to be shooting, too? But for some reason you have no idea if a filter will harm the picture? That is until it jumps up on the spur of the moment?
On the other hand Mr. Campbel's point is well taken. Astro-photography is one of the most critical conditions there is. I don't use a filter than either. Guess what? I remove any filter before hand so I don't lose the “moment”.
Everybody should know and be aware how their photos are going to be used in the end. Facebook? Printed at Walmart? Sideshow on a TV screen. Yeah, a filter is going to ruin these! Whatever. Or, perhaps a fine high-quality professional print. But maybe you are just a pixel-peeper and that's your goal.
Know how your photos are going to be used than decide.
EB
EOS 1DX and 1D Mk IV and several lenses!
