*Note: This tip only really applies to DSLR (Digital Single Lens Reflex) camera users, since the lenses on these cameras have filter threads (required for attaching a photo filter of any sort).

If you look at magazines or postcards, you might notice that the ocean and skies always seem a little bluer or that the grass looks a little greener. And when you go to the exact same location and shoot the same picture (at the same angle), chances are that it looks nothing like the photo shot by the professional.

That’s because professionals (and some budding enthusiasts) use polarising filters - a little piece of special glass that you screw on to the front of your lens that helps cut out reflections.

Please refer to the following pics:

Both pictures were taken in quick succession with the same camera and lens. The weather and lighting conditions didn’t change either. So why do they look so different?

The first shot was taken without a polarising filter, and all of the light from the sky is reflected off the river and the plants. In the second shot, a polarising filter is used to cut off some of the reflections - even off the trees - to produce a much nicer picture.

Why this works:
Basically, all light waves oscillate transversely as they go through any space - the polarity (that is, the angle of oscillation) is mainly dependent on either the source of light or the angle of a plane that reflects the light.

A Polarising Filter basically cuts off light waves along a particular polarity. In photography, a polarising filter is normally used to cut out reflections (rivers, glass doors, etc) and specular highlights on objects (such as the reflective sheen on tarmac during sunset). By doing so, the natural colour of the object (such as the green of leaves or the colour of a car) is more easily captured by the camera.

If you’ve been following closely, you’ll also see that only light of a particular polarity can be cut off with a single polarising filter at a time. Hence, it’s impossible to cut out all the reflections in a given scene, unless there’s only one plane.

The polarising filter itself can be rotated to cut out light from the desired plane of polarity. The best way to see how this works is to try it out yourself.

Why this is necessary:
Strictly speaking, a polariser isn’t 100% necessary for all outdoor shots. After all, there are times when you might acually want reflections in your pictures. They’re also not so good for hand-held night-time photography, since you’ll be cutting off even more light, which would mean even higher required ISO settings or longer exposures. It’s really up to you and how you want to compose a shot.

Additional information:
For digital cameras, you’ll need to get yourself a Circular Polarising Filter (commonly marked as “C.PL” filters). Apparently, standard polarising filters have some unwanted side-effects on the metering systems used and may result in under- or over-exposed shots.

Also, make sure you get a filter in the correct size for your lens - there’s usually a marking on it that says how many mm the diameter of the filter thread is. Unfortunately, most lenses have different filter thread sizes, which means that you’ll have to either buy a few of the same filters or get a large one and several filter adapters. Generally, larger filters tend to cost more.

Conclusion:
If you’re shooting in bright daylight and your shots have too many distracting reflections in them, try a Circular Polarising Filter - sure beats Photoshopping everything later on.