The Chrosziel 110-98mm Step-Down Ring is a precision-engineered mechanical adapter designed for professional cinematography and photography, facilitating the use of smaller-diameter matte boxes and accessories on larger-diameter prime or zoom lenses. Its primary function is to create a secure and concentric connection between a lens with a 110mm front thread or diameter and a matte box system designed for a 98mm thread. This allows cinematographers and videographers to utilize a single, standardized matte box across a range of lenses with varying front sizes, increasing the flexibility and efficiency of their lens kit without requiring multiple, lens-specific matte box stages or complete systems. The ring is machined from high-grade aluminum or similar lightweight yet durable metal, ensuring it adds minimal weight and maintains the structural integrity required to support the matte box and any inserted filters.

The design of the step-down ring is deceptively simple but requires exacting tolerances. It features a male 110mm thread on one side, which screws directly onto the lens's filter thread or a follow focus lens gear with a 110mm outer diameter. The opposite side of the ring has a female 98mm thread, accepting the corresponding male thread of the matte box's adapter ring or a 98mm filter. The precision machining ensures perfect alignment, which is critical for maintaining optical axis integrity and preventing vignetting, especially when using wide-angle lenses. The ring's profile is typically kept as low as possible (slim design) to minimize the distance between the matte box and the front lens element, further reducing the risk of mechanical vignetting.

In practice, this accessory is an essential component of a modular lens support and filtration system. It enables the use of industry-standard 4x4 or 4x5.65-inch filter trays in a 98mm matte box on lenses that would otherwise require a larger, more cumbersome 138mm or 110mm matte box system. By employing a step-down ring like the Chrosziel 110-98mm, cinematographers can streamline their rig, reduce the number of matte boxes needed on set, and ensure consistent filter use across different lenses. Its robust construction and precise fit reflect the professional-grade quality required for reliable performance in demanding film and video production environments.