I'm sure I'm not the first person to experience this, I have a hard time seeing through the viewfinder what affect a CPL is having. As I rotate the filter I can sometimes (but not always) see the image darken (I assume that's near the point of maximum effect, based on the relative position of the sun), but that's about it. I've played around on several occasions and can definitely see a difference once I'm looking at photos on the computer, but really have a hard time predicting what an image is going to look like ahead of time. (By the way, I'm using decent filters... I have a Marumi DHG Super and a Hoya Super - I'd think they're plenty good for my level of experience).