The Chroma CT468.6/4bp He-II 50 × 50 mm unmounted filter is a specialised narrowband filter designed for imaging the ionised helium He-II spectral line at 468.6 nm. This line is an important marker of high-energy astronomical regions and may be used in the study and imaging of the hottest stars and nebulae. Thanks to its narrow transmission band, the filter selectively isolates He-II emission while reducing the influence of light outside the target spectral range.

Key features

• specialised narrowband filter for the He-II 468.6 nm line
• nominal 4 nm transmission band
• designed for imaging emission associated with high-energy astronomical regions
• useful for imaging hot stars and nebulae
• peak transmission near 469 nm
• maximum transmission based on the manufacturer’s spectral data: approx. 96.8%
• unmounted version in 50 × 50 mm format
• intended for demanding astrophotographic and observational applications with monochrome cameras

Kit contents

• Chroma CT468.6/4bp He-II 50 × 50 mm unmounted filter

Technical specifications

• manufacturer: Chroma
• product name: CT468.6/4bp He-II
• SKU / manufacturer part number: 27068
• filter type: He-II narrowband filter
• emission line: He-II 468.6 nm
• nominal transmission band: 4 nm
• peak transmission: approx. 469 nm
• maximum transmission: approx. 96.8%
• filter dimensions: 50 × 50 mm
• filter thickness: 3 mm
• format: unmounted

The Chroma CT468.6/4bp He-II 50 × 50 mm filter is intended for highly specialised astronomical applications where selective imaging of He-II emission in a narrow spectral range is required.