Proper use of circular polarizer

[decisivemoment]

I have a canon EOS 1100D  which I always use with an UV filter.

If I want to use a circular polarizer, do I have to take off the UV filter,

or the polarizing filter may as well be mounted on it?

[hsbn]

More glass = degrade image quality. So to start of, get a good filter. Second, avoid stacking filter if you can. It's ok to leave PL filter on, but you'll lose almost 2 stops of light. If you shoot mainly landscapes, then it may not be a big deal. I have my PL on 80% of the time.

[hernhombeecaryb]

Try it yourself, see what you think. Compare images. Here is what to look for: 

Vignetting: Darkening of the corners and edges

Softening: Loss of detail and vibrancy in colors

Aberrations: Colors bands around edges of objects in image

Shutter speed: You lose 1.5 - 2.0 stops of light,