There are two filters that are essential to landscape photography.
- Circular Polarising Filter (CPL)
- Graduated Neutral Density filter (GND)
Why do we call these filters essential? Well simply because the effect of a polarising filter cannot be replicated in post-processing. On the other hand, a Graduated Neutral Density filter helps give your photograph the extra oomph. Let us discuss these filters and the need for them in more detail
Circular Polarising Filter (CPL)
A polarising filter reduces reflected light. It works by filtering out sunlight which has been directly reflected toward the camera at specific angles. By absorbing reflected light, a polarizer improves colour saturation and contrast. While software post-processing can simulate many other types of filter, a photograph does not record the light polarisation, so the effects of controlling polarisation at the time of exposure cannot be replicated in software. Therefore, if you have water, sky, vegetation or metallic surfaces in your photo frame then a CPL will stand you in good stead.
There are two types of polarising filter: linear and circular. These terms do not refer to the shape of the filter, but rather the way in which the filter modifies the light waves that pass through it. The circular polarising filter, as opposed to a linear polarizer, is designed in such a way that the camera’s metring and autofocus systems can still function. So if you are using a digital camera it makes sense to buy a circular polarizer.
Buy polarising filters on Amazon India.
Graduated Neutral Density Filter (GND / Grad)
A GND is a filter where one edge of the filter is Neutral Density aka Grey and the other edge is 100% clear edge. A GND is built to equalise the exposure in the bright and dark areas of a photograph. This is essential for scenes where you have the sky or the horizon as part of your image. Usually, the lit up sky is orders of magnitude brighter than the ground below it. If you expose your image for the bright sky the ground below it turns into in a dark mush with poor detail. Conversely, if you expose your image for the dark ground below the sky turns white with little or no detail. The grey area in a GND helps equalise the dark and light parts of an image by reducing the amount of light in the bright part of the image.
GND filters come in a drop-in and screw-on variety. Drop-in filters are usually square or rectangular in shape and they drop into a custom holder that fits in front of the lens. A screw in filter works like any other filter and screw into the front of your lens. Drop-in filters are more versatile because you can move them up and down to get different levels of gradation. However, despite their seeming less versatility we recommend a screw in filter for trekking because a) they are quicker and easier to set up b) They are more robust, less prone to damage and do not require a filter holder.
The grey edge in a filter might have a sharp cutoff to white or it may gradually transition to clear edge. These different types are referred to as Hard edge or Soft edge filters respectively.
A GND’s strength is the difference in light transmission between the grey edge of the filter and the clear edge. Each F stop of difference is referred to as 0.3. Thus, 2 F-Stops is 0.6 and 3 F-stops is 0.9. This means a 0.6 GND has a darker grey edge than a 0.3 GND and provides 2 stops of light difference between the grey edge and the clear edge.
Buy 0.6 Graduated Neutral Density filters on Amazon India.