Using Polarizing Filters:
How to use polarizers
There are two main kinds of filters that photographers generally use: color correcting filters and polarizing filters. Color correcting filters are exactly what they sound like; they correct color in many situations where the color of the existing light will result in a bad picture. Polarizing filters are a different kettle of fish altogether. Polarizing filters don't change the color of light, they filter out glare and reflections. This is hugely important in landscape photographs. Light is always reflecting off shiny surfaces in nature; leaves, water, wet surfaces, the sky, and any kind of foliage are always reflecting a lot of ugly, white light that ruin many landscape pictures. Your eye doesn't usually see all these reflections but the camera definitely will. When you use a polarizer on your camera, the picture will immediately become richer and much more colorful. With the glare gone, you see pure color, not color mostly hidden behind the glare. You aren't changing the color or intensifying it, you are simply making the color that was always there much more visible. Using a polarizer can make the difference between a very mundane, blah picture that you toss in the trash can as soon as you see it and a picture that has a chance to be a real work of art. All of the pictures on this page were taken using polarizers.
Polarizing filters are composed of two pieces of dark looking glass sandwiched together into a singe filter. One piece of glass is fixed and the other one rotates. The filter has to be screwed onto the front of your camera lens. This means that your lens has to have filter threads. A few of the less expensive or very small digital cameras don't have lens threads; if this is the case, it is a good sign that it is time to upgrade to a better camera. Luckily, almost all lenses do have threads but they may be small and hard to see, so look carefully. You can buy polarizers at any camera store; just be sure you get one that will fit your lens as they come in many different sizes.
Using a polarizing filter is easy. In the first place they only work when you are shooting at right angles to the sun. They don't work if you are shooting directly into the sun or if the sun is directly behind you. Focus on your scene and then turn the polarizer ring. If there is a lot of light reflecting from the scene, which there almost certainly is, the entire scene will suddenly shift from a lousy picture with flat colors to a gorgeous scene of rich, brilliant colors. It is pure magic, one little twist of the wrist and the picture is suddenly 400% better. It is really unbelievable. One of the most dramatic changes can be seen in a blue sky. Blue skies include a lot of dust and dust reflects tons of light. One twist of the wrist and that pale, nothing sky becomes a deep, rich blue that will really make the picture.
Like everything in photography, polarizers have a negative as well as a positive side. The bad side is that polarizers cut the light entering your camera by about two stops. Since you are undoubtable shooting with an auto exposure camera, the camera will automatically compensate for the loss of light. However, if you have your lens stopped down to a small f-stop to get the maximum depth of field, then you are already shooting at a very slow shutter speed. And that extra two stops you lose using a polarizer may be too much, especially if there are things like flowers or leaves in your picture that need to be absolutely still and the wind is also blowing. There are two ways out of this quandary: wait for a lull in the wind (be patient, it will almost always stop for a few seconds at least) or increase your ISO (film speed). You can get your lost two stops back by increasing ISO by two stops. Don't do this unless you have a fairly good camera though; increasing ISO will almost always add nasty digital grain to your picture. The best way to see if you are adding digital garbage to your picture when you increase ISO is to test it. Shoot some pictures at high ISO's and then look at the pictures. To see grain you will probably have to load the picture into your computer and blow it up to a fairly large size. Look in the shadows and darker areas of the picture for red, purple, blue or other colored speckles and blobs. This is grain and it's not pretty. On the other hand if you can live with a small snapshot, the grain probably won't even be evident in very small sizes.
One other drawback to polarizing filters is that, like all other screw-on filters, they are just one more piece of glass in front of the lens, all of which will cause a slight drop in image sharpness. However, the positive effects of polarizers are so great, that I for one almost always elect to trade a tiny amount of sharpness for a huge increase in color quality.
In spite of the drawbacks, I really do like polarizing filters. In fact, I like them so much, I tend to keep them on my camera almost all the time. However, there are times when it is best not to use polarizers. I don't use polarizers when it is getting quite dark and I need all the light I can get. I don't use them when I am shooting into the sun or with the sun at my back since they don't work in these situations anyway. I don't use them when I need every ounce of speed I can get to stop moving vegetation. Sometimes when the blue sky is pretty dark already, a polarizer will turn it almost black so I will take the filter off. But if polarizers are working well, and I have enough speed, I absolutely use them in almost every shot. Polarizers are one of the major differences between the pictures of a professional and an amateur photographer.
One more small word of advice about polarizers. In the heat of shooting, it is very easy to forget you have a polarizer on and also very easy to forget to use a polarizer when you need one. I can't tell you how many times I have made these mistakes. There is nothing like shooting a wonderful scene until the last scrap of light is gone and then realizing that the picture would have been a thousand times better with a polarizer. Or, shooting a late evening scene with a slight wind that is moving the foliage just slightly and then realizing, when it is too late, that you have a polarizer on and all the shots were ruined because of flower movement is just about as wonderful an experience. If you are going to use polarizers regularly, you have to stop and think about whether it is on or off. Since I am rapidly approaching early senility, I have a small tag on the back of all of my cameras that says "POLARIZER STUPID!!!"
I could give you hundreds of instances when polarizers have saved the day, or at least the picture, for me. Here is one: I was on a beach in Arcadia National Park in Maine just the other day. The beach is called Wonderland Beach. When I got there after a mile walk, I took a quick look and didn't see any wonderland at all. I thought it was plain old ugly. But I was there, so I set up my camera and started shooting around here and there to see what I could dig up. Nothing, nothing, nothing. And then I started noticing that some of the large boulders were an interesting warm, orange color and had interesting shapes. So I shot these for a while and got some so-so stuff. Finally I wandered right down to the water's edge. The tide was at an absolute low and I had to wade out through a lot of goopy seaweed and slippery rocks and plain-Jane tide pools to get there. When I did finally get there, I saw that the rocks right at the edge of the sea were the same orange rocks I had been shooting earlier, but these were much better because they were wet. So I set up a few compositions and shot a few of what I thought were kind of OK shots. (The kind I throw away when I get home.) Finally I realized that the rocks were wet and shiny and glary and that I didn't have a polarizer on my camera. So I put one on. When I turned the polarizer ring, I was absolutely floored, stunned, astounded. I know that sounds like hyperbole, but it was true. The polarizer had turned a ho-hum scene into what really was a wonderland of brilliant oranges and blacks and white water. By using a little persistence and a polarizer I actually made some shots that I thought were quite good, where before I had not seen a single thing I deemed worthy of shooting. I had totally overlooked the wonderful color of his beach. Two lessons here: one, be persistent, use your eyes, keep shooting and surprising things may happen. Two, try a polarizer, and more wonderful things may happen.
Below is one of the pictures I took at Wonderland Beach.
Wonderland Beach, Acadia National Park, Maine