Sony Drop-in Circular Polarising Filter For Sony FE 400mm F/2.8 GM OSS Lens

This Sony Drop-In Circular Polarising Filter effectively reduces reflections and glare by filtering out polarised light from non-metallic surfaces. Designed to fit within the accessory filter slot of the Sony FE 400mm f/2.8 GM OSS Lens-whose large front diameter can't accommodate a screw-on filter-this filter achieves its effect behind the main glass elements for optimal image quality.

The light from the sun naturally becomes partially polarised due to reflecting off electrons in air molecules, causing the light to scatter into what appears as haze. A polarising filter arranges, and filters, this directionally polarised light perpendicularly to the reflected light, allowing for the absorption of much of this light. This results in a noticeable reduction of glare and reflections from non-metallic surfaces and an increase in the saturation of skies and foliage.

A circular polariser only differs from a linear polariser in that it contains a quarter wave plane in addition to the linear polarising filter. The addition of this quarter wave plane is to circularly polarise the linearly polarised light for the use of auto focus and exposure functions. Due to how the light is broken down and filtered with a linear polariser, auto focus and exposure accuracy become skewed during use. When the light becomes circularly polarised, it permits the use of these functions.

This filter is constructed from optical glass for clarity and includes an integrated locking mechanism to secure it within the compatible lens, as well as an external dial to allow rotation of the filter glass for control of the polarisation effect.