A CPL cuts out reflections and deepens natural colours of a scene. Rotating the CPL changes the direction of polarisation and can have a dramatic effect on the final image. CPL’s also acts as a very light ND filter (blocking approximately 1-1.5 stops of light).
Common uses for a CPL include removing glare and reflection when shooting around water, bringing out the deep greens of a forest scene and are a great tool when shooting waterfalls to remove the reflection from the water.
This image was taken as an example to show the effect a CPL can have to remove glare from the top of the water. Being 90 degrees to the light source you can see the polariser is working to its maximum potential.
NiSi has three types of CPLs
A ‘screw on’ CPL is attached directly to the lens and does not allow a filter system to be placed over it. This is good for handheld shooting and can be rotated directly.
A square Linear Polariser which requires a square filter system. These are available in 100x100mm, 150x150mm and 180x180mm. Here is a tip how to use them:
The other sort of CPL is a circular filter which can be attached to the filter holder ring itself. This can be rotated through a gear mechanism on the filter holder.