Chroma Ha5LRGB 65 × 65 mm unmounted filter set (SKU: CT-27110-Ha5LRGB-65X65) is a set of five filters designed for astrophotography with a monochrome camera. The set combines broadband Luminance, Red, Green, and Blue filters with a narrowband H-alpha filter featuring a 5 nm bandwidth. It enables natural-colour LRGB data acquisition and the addition of high-contrast hydrogen-emission signal from nebulae and star-forming regions.

Key features

• complete set of five filters: H-alpha 5 nm, Luminance, Red, Green, and Blue
• coordinated LRGB filter passbands providing high transmission, consistent colour balance, and strong out-of-band blocking
• narrowband H-alpha filter with a 5 nm full width at half maximum, balancing strong contrast with higher signal throughput than narrower 3 nm variants
• centre wavelength of 656.3 nm for the H-alpha filter, corresponding to the emission line of ionised hydrogen
• peak transmission of approximately 99% for the H-alpha filter
• square 65 × 65 mm format for large filter wheels and holders accepting unmounted filters
• thickness of 3 mm and blackened edges reducing internal reflections
• durable sputtered coatings providing stable spectral characteristics
• surface accuracy of λ/4 or better
• standard version intended for optical systems with a focal ratio of f/4 or slower

Included components

• filter H-alpha 5 nm Chroma 27002, 65 × 65 mm, unmounted
• filter Luminance Chroma 27040, 65 × 65 mm, unmounted
• filter Red Chroma 27041, 65 × 65 mm, unmounted
• filter Green Chroma 27042, 65 × 65 mm, unmounted
• filter Blue Chroma 27043, 65 × 65 mm, unmounted

Technical specifications

• manufacturer: Chroma Technology Corp.
• series: Ha5LRGB
• product code (SKU): CT-27110-Ha5LRGB-65X65
• number of filters: 5
• filter types: H-alpha 5 nm, Luminance, Red, Green, Blue
• application: LRGB and H-alpha astrophotography with monochrome cameras
• construction: unmounted
• shape: square
• dimensions of each filter: 65 × 65 mm
• filter thickness: 3.0 mm
• edge finish: blackened
• coating type: hard sputtered coatings
• surface accuracy: λ/4 or better
• recommended optical-system focal ratio: f/4 or slower
• centre wavelength of the H-alpha filter: 656.3 nm
• full width at half maximum (FWHM) of the H-alpha filter: 5 nm
• peak transmission of the H-alpha filter: approximately 99%

Combining a complete LRGB set with a 5 nm H-alpha filter allows one filter set to record natural object colours and render hydrogen structures in emission nebulae more clearly.