pprice wrote in post #5962851
I just bought a circular polarizer today and I am going to wait for the sun to drop a little more and take my car to the lake to try again (with a better background).
I do have another question about this filter though, how do you know when it is needed and when it will hurt more than help? Is there a rule of thumb or does it just come from experience?
I don't think that this one has been addressed yet, so I will. If you are shooting roughly in the direction of the sun or away from it, the CPF will not be of any use other than making the image darker which is not something that you would normally want to do. The best direction to shoot is perpendicular to the azimuth angle of the sun (if the sun is around 270° then shoot approximately towards 0° or 180° ). The best time to use it is either early to mid morning or late afternoon until the sun is low. Also, you will need to rotate the filter while looking through the viewfinder to get the effect that you want. I do not think that the CPF's have as much impact on an image as the old ordinary plain vanilla polarizing filters.
Just in case anyone is interested, the only difference between the two types is that the CPF is followed by a quarter-wave plate that is set for about the midpoint of the human range of vision. That is its shortcoming -- it only works as a true circular polarizer at that one point and then becomes increasingly eliptical as the light goes towards either blue or red. At either end of our vision range, the filter is function more like a linear polarizer than a circular polarizer. The only reason that CPF's ae even used is that the focus system on some, maybe most, digital cameras does not work reliably with ordinary polarizers. I have an old plain polarizer so I need to try it out on my camera to see if it is an issue.
Want to see a cool effect with circular polarizers? Stand in front of a mirror and hold the CPF in front of one of your eyes so that the side that screws into the lens is towards your eye ... you can see your eye in the mirror. Now, flip the filter around and do the same thing ... suddenly the filter just looks black.