Originally Posted by laboitenoire
I got a Tiffen CPL yesterday as an 18th birthday present. Should be fun to shoot with once the weather improves. I didn't realize that CPL filters block so much light from coming through!
In a photograph without a cpl, you're collecting both the specular (direct) component of light which is what you want, as well as a diffuse of reflected component. The sum total of these two components is your total measured light that is accounted for by your camera.
With your cpl, you reject the reflected or diffuse compnent thus reducing a large portion of the total light reaching the sensor and hence your're seeing less total light. But this is exactly what you're asking your cpl to do. throw away reflected and/or diffuse light which does not contribute spectral detail of your image.
Newer (and more expensive) cpl's use fancier coatings and polarizing media to reduce overall light loss while still achieving the polarizing effect, but you wind up paying alot more $$$ for a relatively small difference in exposure.
Take some shots with your new cpl in place and make sure your images look good at 1:1. I recently shelled out $210 for the newest latest and greatest 77mm Hoya HD cpl only to have it be defective, ( images at 1:1 looked terriblely noisy). Sent it back and bought a Nikon cpl which works beatifully. I also Have a 77mm Promaster cpl that works very well also.
Clouds, water surfaces, and leaves in the sun look so much better with a cpl.
Have fun, pics.....