OPTOLONG ND3.0 Astronomical Solar Filter Neutral Density Filter ND Filter for Transmission Reduction 2-Inch/1.25-Inch

Introduction:
- Neutral Density (ND) filters are designed to reduce transmission evenly across a portion of a specific spectrum. ND filters are typically defined by their Optical Density (OD) which describes the amount of energy blocked by the filter. A high optical density value indicates very low transmission, and low optical density indicates high transmission (Equations 1-2). ND filters can be stacked to achieve a customs optical density. To calculate the final system OD, simply add the OD of each filter together.

Features:
- Substrate: optical glass
- Thickness: 1.85mm
- T=0.1%
- Surface quality: 60/40
- Transmitted Wavefront RMS: λ/4
- Parallelism: 30s

Package Included:
- 1 x Filter