There is a tremendous amount of reflections when we’re out in the wilds shooting. You might have never have noticed it, but it’s there. This reflection is coming from the sky, the blue sky. The vast majority of the time, the reflection has a blue cast to it which literally reflects off the subject’s color. This blue cast affects the color of the elements in your image (if at the right angle to the sky) giving them all a blue tinge.
Many attribute great color in a nature photo to the use of vivid white balance when in actuality the great color was a result of proper use of a polarizer. Proper use of a polarizer removes the blue reflection so the color we see with our eyes is seen and recorded by the camera. It is essential you understand that the proper use of a polarizer is to remove reflections and not make the sky dark blue (though you will have the side effect at times). There are times when a polarizer is used correctly it will also make the sky darker, but to see proper polarization you don’t look at the sky, but at the ground.
Using a polarizer correctly takes talent just like using any other tool in photography. All you have to do is rotate the filter, right? That is correct, but when you’re rotating the polarizer you need to look through the viewfinder and look for the blue to disappear (does mean you only use the polarizer if you have a bright blue sky overhead? perhaps). You don’t look at the sky, but you look at the ground. You rotate the polarizer looking at dirt if possible until the ground appears a nice, warm, rich chocolate moose brown (get it, chocolate moose, Moose’s technique?). Normally, the ground will have a cold, bluish, dead brown color when not viewing through a polarizer properly rotated. You want that ground warmed up to that rich chocolate moose brown because then you know you’ve removed the blue from the scene.
What if the ground is not your subject, does this technique work? Polarizing light is another one of those physic things photography is so wrapped around. Technically, only objects approximately 90 degrees to the film plane are affected by a polarizer, that’s the full effect of the polarizer (and if the sky is in the photo, it turns dark blue at 90 degrees from the sun). In practice, you can see the effect of a polarizer even though the object might not be a true 90 degrees. That’s why you rotate the polarizer and look. I recommend first looking at the ground because dirt is pretty much dirt and a lot easier for folks to understand the polarizing effect than looking at a critter or tree bark. That’s because polarizers are not a cure all, but just another tool.
They don’t always help! If you’re shooting in overcast light for example, a polarizer will have minimal effect. If you’re shooting a backlit subject, the polarizer will do nothing for you. Shooting a backlit subject means you’re shooting with the lens pointed towards the sun and at that angle, the physics are all against you.
Do I use the Polarizer with Digital? YES! Can you do the same thing in Photoshop? NO! Do I use a polarizer all the time? NO! Do I use the Moose Polarizer? NO, since I’m not using the 81a filter anymore. I prefer the Nikon Slim Polarizer personally and regrettably, carry two sizes now because of my lens selection.