In article <01bb9a06$806981a0$b3dbfccd@MDRDSR>, mdrdsr@fred.net says...

>I have been in the habit of using a Circular Polarizing filter all of the
>time (ie I never remove it from my Nikon 6006). I have a CPF on both my
>35-80mm and 70-210mm Nikon lenses. Is this a good habit? I generally
>shoot outdoors at nature and/or people. I am now noticing that it
>effectively increases my f-stop and decreases my shutter speed.
>
>I have just ordered a SIGMA 400mm 5.6 APO AF Mac. lens and a NIKON 28mm 2.8
>lens. Should I even consider using a CPF on the 400mm lens? I suppose
>that use of the CPF should be situational and I should not use it all of
>the time but only when I want to remove "reflections/glare". What about a
>lens hood on the 28mm? I notice with my 35-80 zoom I sometimes get a
>"tunnel" effect from the hood and the pictures have a "round shadow".

I shoot a lot of color, some of it for travel brochures, and I have yet
to use a polarizer (though I have several). If you choose the subject, lighting, and film well, there is little advantage to using a polarizer
most of the time, and there are the disadvantages of loss of effective
film speed, slight loss of sharpness, potential vignetting problems, and having odd color casts and unnatural-looking colors in your photos.
Why use a polarizer?
Hope This Helps