High contrast scene when the sun is right above of the horizon needs to reduce the amount of light reaches the sensor of the camera to counteract overexposed part of a scene. The effect of using the filter gives you the properly exposed picture with natural and clean colours without using of HDR effect.
Irix Edge Reverse Neutral Density filter do not affect the colouration of the image and the 0.9 density provides a 3 stop reduction in light from entering the lens in the central part of an image. All of the Irix Edge filters are characterized by the highest precision and optical quality to be able to meet the image quality generated by Irix lenses. Both surfaces of the glass filter are covered by the multilayer anti-reflex and water/oil-proof coating providing high light transmission and natural colours in any weather conditions.