In case you don't know what a circular polarizer is, it is a filter that screws onto the end of your lens to allow you to polarize the light coming into your lens. It is used for two main purposes:
- Reducing reflections and glare from water, glass, etc.
- Darkening skies
I used a polarizer in Kamloops to photograph the salmon run. It made a dramatic difference in the ability to see the fish under the surface of the water.
I used a polarizer yesterday at Elkhorn, MB to perform #2, darkening the skies.
I didn't edit the Elkhorn photos at all except to adjust the crop a tiny bit to get the same composition, and I applied the same lens correction to both in Lightroom.
You can see how the polarizer brought a lot more interest to the sky. The sky is darker and the clouds are better defined.
I like dark blue skies so I like to use a circular polarizer... when I remember it. The only downside to using a polarizer is that it reduces your exposure by a couple of stops, so you need a bright day to avoid reducing the light so much that you have to use a high ISO or slow shutter speed.
A circular polarizer is pretty much the only filter that you can't totally simulate in Photoshop.
|Hoya PRO1D circular polarizer|
Personally I use a Hoya 58mm Circular Polarizer on my 18-55mm lens and a 67mm Hoya PL-CIR on my 70-200mm lens. You have to get the right size for your lens! I recommend you get a slim frame polarizer so you don't have any vignetting problems. (note that these are affiliate links, in which I get a commission, at no extra cost to you)
This video shows you how circular polarizers are used. Basically you screw it on the end of your lens, and when you are ready to shoot, you turn the polarizer until you get the amount of polarization that you want.
To recap, a circular polarizer is used to cut down glare and reflections, and to darken skies. It's a useful item to carry around with you, especially when shooting outside or when photographing water. Enjoy!