The HOYA HD Mk II series features 16 layers of anti-reflective coatings with HOYA's water repellent and stain resistant coatings making filter maintenance easy. The UV & Protector incorporate chemically hardened optical glass which provides excellent lens protection against accidental damage, and the CIR-PL features High light-transparency UV-absorbing polarisation film for faster shutter speeds.
Light rays which are reflected by any surface can become polarised and polarising filters can be used to select which light rays enter your camera lens. CIR-PL (Circular Polarising) filters allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. They also enable colours to become more saturated and appear clearer with better contrast. This effect is often used to increase the contrast and saturation in blue skies and white clouds. HOYA's polarising filters do not affect the overall colour balance of a shot.