What is a circular polarising filter?
Polarising filters are also called CPL filters. Polarising filters are the most commonly used filters in photography: they can be used to easily remove unwanted reflections from a scene. In addition, a polarising filter can be used to enhance the contrasts of an image. These two properties make the filter non-reproducible in image processing, furthermore its uses are manifold in many areas of photography. In the following article we will inform you about how to use these filters, what effect they have on the image and what different types there are.
Using a polarising filter
Using a polarising filter is very simple and intuitive. First you attach the filter directly to the front lens or to the adapter ring of the filter holder. Then the filter can be rotated directly on the lens of the camera or, if you use one of our filter holders, by the corresponding wheel on the holder. Both in the live view and when looking through the viewfinder, you can see how the effect changes depending on the rotation. Once you have set the effect you like best, you can use it. If you use our K9 filter holder, you can also fit up to 3 SLIM rectangular filters, such as an ND filter for long exposures, together with a GND filter to balance the exposure of the sky.
When is it useful to use polarising filters in photography?
CPL filters are mostly used photographically when reflections and mirroring on surfaces and objects that are not metallic are to be minimised or prevented in order to thereby direct the focus more on the subject itself and make the colours appear more vivid, especially when photographing landscapes and architecture. Minimising reflections is also often used when photographing products. This is because there is still no image editing programme that can imitate the function of a polarising filter.
As already mentioned, a polarising filter additionally increases the contrasts & colours by filtering out complementary polarised light, for example the reflected blue of the sky on the green of grass and leaves. This makes the colours of the object in focus look much richer. Similarly, a polarising filter brings out the contrast between the blue of the sky and the white of the clouds, for example. By turning the polarising filter, it shows its function by filtering the light waves. The result of this process is then directly visible in the viewfinder of the cameras. The colours appear more intense, haze and reflections are reduced and the sky gets a clearer structure as the clouds stand out more clearly against the blue of the sky. Water surfaces can also be photographed clearly and almost completely transparent.
What effects can be achieved with the help of a polarising filter?
- A clear and almost dramatic sky drawing
- Intensification of colours & contrasts
- Reduction or complete avoidance of reflections and mirroring on non-metallic surfaces (water surfaces, windows etc.)
- Generally filtering polarised light
When are these polarising filter effects useful?
- In product photography (reduction of reflections on surfaces such as wood, plastic, etc.)
- Architectural photography (avoiding reflections on windows)
- Landscape photography (transparent waters, more intensive colours and clouds, more clearly recognisable structures and contrasts)
How do I apply a polarising filter correctly?
The filter is first screwed directly onto the camera lens or inserted into one of our filter holders. The effect of the polarising filter is then achieved by turning the filter. Turning the filter anti-clockwise increases the effect and turning it clockwise reduces it (sometimes the other way round). Our polarising filters work steplessly and can therefore be adjusted exactly as desired.
Sometimes the images appear a little darker with a polarising filter. Instead of increasing the ISO value of the camera, we recommend shooting in RAW format. This allows you to brighten the image afterwards when importing it (e.g. into Photoshop) and to readjust the parameters.
What is the difference between circular polarising filters and linear ones?
While circular polarising filters can be used on SLR cameras as well as on other cameras, linear polarising filters are not suitable for SLR cameras, as the measurement technique can cause misrepresentations. Filtering only works in one direction with CPL filters, whereas linear polarising filters can be used in both directions.
Circular polarising filters
Linear polarising filters
Suitable for SLR cameras
Unsuitable for SLR cameras
Polarising effect in one direction only
Works in both pass directions
Usually more expensive than linear polarising filters
How can our polarising filters be cleaned?
The best way to clean CPL filters is to follow the steps below. This preserves the quality of the filter and prevents it from getting scratched:
- First, you should remove the coarse dust with a small bellows or similar.
- Then you can clean the polarising filter with a microfibre cloth.
- For stubborn dirt, you can use a so-called lens cleaner solution or distilled water for cleaning.
It is important not to use any other chemicals when cleaning the filters, as these could damage the coating.
Can a polarising filter be used with different lenses?
Yes, it is of course possible to use one CPL filter for several lenses. You can work with a step-up ring. If you plan to do this, you should buy the polarising filter for the lens with the largest filter diameter. The step-up rings can then be used to create a connection between the different filter thread diameters.
What is polarised light?
Light propagates in the form of waves in the atmosphere, and these waves oscillate in a certain direction. The direction of oscillation of the light waves is determined by the so-called polarisation of the light. Put simply, this means that a light wave can oscillate from left to right, which is then called "horizontal". However, if the light wave oscillates from top to bottom, this is called "vertical". Of course, there are also all the intermediate stages between horizontal and vertical directions of oscillation, because normally light contains a relatively even mixture of all directions of oscillation. This light is then called "unpolarised" because it cannot be assigned to any single direction of vibration.
What is successful landscape photography?
Like many things in life, a successful landscape photograph is a matter of opinion and lies in the eye of the beholder. So here we can only tell you what makes a great landscape picture for us. Apart from that, however, most people consider a photograph to be perfect if it meets the following requirements:
- The motif should be atmospheric!
- The picture should be emotional, i.e. it should make the viewer want to be there.
- It should be sharp, i.e. show as many details as possible.
- The picture should be vivid, i.e. show as many brilliant colours as possible.
- It should be vivid, i.e. have a three-dimensional effect.
- The chosen motif should be personal, i.e. reflect what you have seen yourself.
If you take these points into account and try to implement them, shots in landscape photography should be almost perfect.
- A polarising filter clearly reduces reflections and deepens the colours of a scene. Turning the CPL filter changes the polarisation direction of the light and can thus dramatically change the effect of the shot.
- This also acts as a very light ND filter (blocks about 1-1.5 stops of light).
- Kase offers three types of polarising filters. One is screw filters, which can be attached directly to the lens. These are good for handheld shooting and can be rotated directly on the lens. The other type of CPL filter, is also a round filter, which can be attached directly to the filter holder ring of the Kase filter system. The filter can then be rotated by an external wheel on the filter holder. We also offer rectangular polarising filters that can be inserted into the slots of the filter holders.