What is the best way to use a polarizer?

When I bought the 28-135mm lens that has lost some time to a 50mm f/1.4, it came with a polarizer. I've never figured out how best to incorporate it into shots. Would someone be able to offer some advice on how best to use it/when best to use it?

Use it if you want to cut glare in order to improve colour saturation or kill reflections.
Also, since light from a clear sky is polarized, you can use a filter to darken this, making it bluer and helping with dynamic range.

Mount the filter, and looking through the viewfinder rotate the moveable part until you get the effect you want. For the sky, keep in mind that the effect is greatest at an angle of 90° to the suns position (that actually describes a cone with you as the apex). That can cause problems in wide angle shots with big changes in sky brightness across the frame, but you may not see that at 28 mm.

Thanks! This stuff seems like its so simple, I don't know why I can't wrap my head around it myself.

Put it on your camera on a sunny day and turn the filter round to see the changing effect. Also look through it with even just your eyes over a pool of water and turn it round to see the the effect of cutting out glare.

Can be a useful filter. Cuts the light reaching your sensor by a couple of stops

EOS_JD wrote in post #7270463
Put it on your camera on a sunny day and turn the filter round to see the changing effect. Also look through it with even just your eyes over a pool of water and turn it round to see the the effect of cutting out glare.

Can be a useful filter. Cuts the light reaching your sensor by a couple of stops

Or a computer display. At one point it'll be completely black.

Do make sure it is a circular polarizer as these are needed for digital cameras. It should be marked as "C-PL", or maybe "PL-C", but not just "PL".

Or, check for yourself.
Look though the filter into a mirror so that you can see the filter through the filter, if you get my meaning. Now flip the filter so its other surface is facing the mirror. If, in one orientation it passes light and in the other it doesn't, you've got yourself a CPL. If it passes light both ways, it's a PL. It's a cool trick!

Vascilli wrote in post #7270473
Or a computer display. At one point it'll be completely black.

True only for LCDs.

Thanks again, all. I'll try this at home tonight. I really want to get better at using my camera, but between figuring out the body, the lenses, the settings, the lighting, and the processing, I am making myself crazy....

Alex, a polarizing filter will affect reflections in NON-METALLIC surfaces. Reflections on water, glass, automobile paint (but not a chrome bumper), etc., are fair game for modification with a polarizing filter.

I have a question about Polarizers. When I take my B+W slim circular polarizer and look through it while holding it to the computer monitor it turns black like it was mentioned here but when I do that with the B+W kasserman circular polarizer it just gets a bit bluer but it never turns dark or black like with the other one.
What are the differences? I thought the kasserman ones are superior but they don`t seem to do much.

A polarizer will basically do this:

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alexwinsberg wrote in post #7270371
When I bought the 28-135mm lens that has lost some time to a 50mm f/1.4, it came with a polarizer. I've never figured out how best to incorporate it into shots. Would someone be able to offer some advice on how best to use it/when best to use it?

The best way? Hard to tell, although I "see" the use of polarizers just like when fishing while wearing a set of polarizing sunglasses. Without these glasses, it's very difficult to see the fish nearby when light reflects on the water toward your eyes blinding you. Wearing polarizing eyeglasses allow your eyes to block the light coming straight toward your eyes, making it easier for you to see the fish. Have you ever taken a photo through glass, such a person sitting in an automobile? The glass or windshield reflects light right into the lens. In this case, a polarizer blocks some of this unwanted light.

I used a cheap polarizer to take this photo. You will notice that you can see some of the sandy bottom: