K&F 40.5MM KU12 Classic Series, Blue-Coated, HMC CPL Filter, Japan Optics

C Series — polarising filter 40.5 mm, cuts reflections and deepens colour.

• Screws onto a lens with a 40.5 mm thread.

A polarising filter takes the glare off water, glass and foliage, and with it brings out the colours that were hiding underneath. The sky darkens, clouds stand out, leaves stop flaring white and you can see through the surface of water. The effect is set by rotating the filter and is strongest at right angles to the sun; it cannot be recreated in post, because it is a property of the light rather than a colour in the file.