46-212 25 mm Dia. Hoya ND-50 Absorptive Neutral Density (OD 0.3) Color Filter; t=2.5 mm 400-700nm

The 46-212 is a 25 mm diameter absorptive neutral density color filter, manufactured by Hoya and distributed by Edmund Optics. This filter is designed with a neutral density of 0.3, often denoted as ND-50, which reduces the light intensity without altering the color composition. The filter's primary use is to balance the light levels in a scene, making it an essential tool for photographers and cinematographers.

The filter is made of UVFS Mal-1965 material, a type of glass known for its excellent optical properties. It has a thickness of 2.5 mm, providing durability and resistance to distortion. The circular shape of the filter allows for easy mounting and alignment in optical systems.

The filter's coating is another notable feature. Both the front and back surfaces are coated with EDM 48-524, a coating that enhances the filter's performance by reducing reflection and improving transmission. This coating ensures that the filter performs optimally across the visible light spectrum, specifically within the 400-700nm range.

The filter's geometry, including its diameter and thickness, is designed to conform to the standard specifications for thin lenses. This design ensures compatibility with various optical systems and equipment.