Polarizing filters can reduce, and sometimes even remove, unwanted reflections from your images, and in doing so often increase color saturation. But mostly they’re used to make blue skies bluer, clouds stand out in dramatic fashion also make a rainbow more visible and help out when you’re photographing foliage by reducing reflections on leaves. Let’s look at a few areas where polarizing filters can have the biggest impact…
When shooting a picture of water adjusting your polarising filter will mean you see into the water differently, cutting out glare and even changing the colour of the water. For example when I was snorkelling off a boat off the coast of Indonesia a few years ago I took a series of photos using a polarising filter that made the water look crystal clear and a bright blue color. Without the filter the shots had nowhere near the same impact with a big reflection being picked up off the top of the water and a more murky color.
Similarly, the color of sky can change remarkably using a polarising filter. Rotating the filter you’ll see a blue sky change from a light pale blue color to a vibrant and deep blue color (depending upon where the sun is). A polarising filter can cut out a lot of the smoggy haze that is often in city shots.
Polarizing filters cut down the reflection that many objects have (even those that you might not think reflect at all). This makes the colors of some of these objects more vibrant. For example out in the garden you might notice foliage on trees looking greener than you would get without the filter.
Shooting through glass can be a real challenge at times and using a polarising filter can definitely assist in cutting down distracting reflections or glare. Similarly photographing shiny objects (like a new car for instance) with a polarising filter will change the way reflections are treated.
Polarizers Change Exposure
One factor to consider with polarising filters is that they change the exposure needed for a shot. When you see a polarising filter you’ll notice that it looks quite a lot like a sunglasses lens (see below for how you can actually use sunglasses as a filter). The filter is dark and works by cutting our some of the aspects of light (similarly to sunglasses). As a result less light gets through to your image sensor and you’ll need to either use longer shutter speeds, a larger aperture or to beef up your ISO setting to account for this. The difference that you’ll need to account for is 1-2 stops. It’s for this reason that you won’t want to use a polarising filter at night.
Choosing a Polarizing Filter
Polarizers come in two main types: Linear and Circular. Circular polarizers, or CPLs for short, are designed to not confuse the auto focus or metering systems on modern cameras, so this is the type you’ll need to buy for your DSLR.
Take note of the diameter of your lens before making a purchase as there is a large variety of lens sizes. There is a variety of brands and qualities of filters available on the market. Keep in mind that polarizers are not cheap filters (when compared for example with UV filters) and that they get more expensive the bigger the lens diameter that you have.
Hoya is one of the most respected filter brands, and if you can afford it, go for one of its “HMC” Multi-Coated models for better quality.
Polarizing filters are quite thick and can sometimes darken the corners of ultra wide angle lenses. To avoid this, buy a thinner polarizing filter.
Using a Polarizing Filter
These filters are easy to use. Most of you will use a circular polarizing filter which allows you to adjust how it impacts your shots but simply rotating the front element of the filter. As you do this you’ll notice that colors and reflections in your shot change. Once you’ve got it to a point that you like simply take the shot.
For the greatest impact try to keep the sun at 90° to you (ie to your side – not at your back and not shooting into the sun). This will help your polarizer to have the greatest effect.
Be aware that shooting in low light, overcast days or at night with a polarizer is not advisable – it’s like wearing sunglasses indoors and will cut down the amount of light getting through to your image sensor.
Tips for taking great photos using a polarizing filter:
- Though a polarizer is handy and versatile, it’s not recommended that you keep it on your lens all the time. It will darken your view of the scene (it cuts down 1.5 to 2 f/stops of light), so if you’re not out to banish reflections or increase color saturation in the sky or in water it’s best to take it off.
- That loss of light isn’t anything to worry about when you’re using a polarizer for a specific purpose, though. Your camera’s meter will read the light coming through the lens and adjust to provide the correct exposure.
- When using your polarizer to darken the sky, the direction in which you shoot is the key to getting the most dramatic effect. Here’s what to do: hold your hand in pistol fashion with your index finger and thumb as the barrel and hammer, respectively. Point the barrel at the brightest part of the sky, and the hammer will be pointing at the area of the sky that will be most affected by the use of the polarizer.
- Seeing is believing, so the best way to appreciate what a polarizer can do is to take your DSLR and a favorite lens down to your nearest dealer on a sunny day and try one out.
The extent that polarising filters work varies from situation to situation (often dependant upon the amount of sunlight) so it won’t have a massive impact in all situations – but in some (especially bright sunny days) the impact can be quite staggering.(via Digital Photography School, via DSLR Tips, via Nikon U.S.A.)