First and foremost, the most important filter you need for your camera kit is the UV filter. Though it only plays a small role in reducing the UV light within your scene, it doubles as the most inexpensive protective filter for your valuable lens. You can scratch and crack a UV filter for around $20 a pop (or you can skip it and end up paying a lot more for a new lens). The UV filter is also commonly known as the protective filter.
For landscape photography, you cannot go without a polarising filter. In the era of auto focus, a circular polarising filter (or CIRPOL) is the best option as helps increase the colours in your scene while also reducing and managing reflections from non-metallic objects. That means it’s useful for capturing the deep colours of your scene while minimising glare or reflections off water.
A neutral density (or ND) filter is next on the shopping list. This reduces the intensity of your scene by allowing less light through. The longer exposure time is perfect for capturing moving water or clouds whisking across the sky. Choosing the right ND will be a matter of how extreme you wish to push your exposure times, with filters ranging from one stop darker (ie. half your usual brightness) to as much as 10 stops less.
In scenes with a big difference between the exposure value of the sky and foreground, such as a beach sunset, you need a graduated ND filter. These filters have a graduated density from top to bottom, or vice versa, to allow you to adjust the brightness of lighter areas for a more balanced range of exposure. Otherwise your camera will expose correctly for the brighter sky, rendering the foreground as very dark. With a graduated ND filter you can capture the sunset as well as the details of the sand or rocks.
In the days of film photography the photographer would use a warming or cooling filter to adjust the colour temperature of their scene; brown or orange to warm, blue to cool. Now, we tend to leave colour adjustment until post production. While some of the other effects described above can be achieved via a good post-production program such as Adobe Lightroom, it is almost impossible to correct the light or exposure time of a photograph after the event.
Award-winning landscape photographer Cameron Blake runs weekend workshops and six-day tours on the Overland Track.