Chroma OIII 3 nm 2" (27006) — ultra-narrowband, M48 threaded ring The Chroma 27006 OIII 3 nm bandpass filter isolates the 500.7 nm primary emission line of doubly ionised oxygen, the next most common nebular emission after H-alpha. Its ultra-narrow 3 nm passband gives maximum contrast and background suppression, ideal under light-polluted skies or bright…
Manufacturer model: Chroma 27006 OIII 3nm, 2-inch M48 threaded ring · Specifications checked against manufacturer data on 2026-11-03
The Chroma 27006 OIII 3 nm bandpass filter isolates the 500.7 nm primary emission line of doubly ionised oxygen, the next most common nebular emission after H-alpha. Its ultra-narrow 3 nm passband gives maximum contrast and background suppression, ideal under light-polluted skies or bright moonlight.
Chroma sputtered coatings
Made on a single high-grade glass substrate with hard sputtered coatings and no lamination, the filter withstands humidity and temperature extremes. The primary coating is on the front and an AR coating on the back to prevent ghosts. Chroma publishes measured spectral data for this filter collimated and at f/2.5 to f/5. For systems around f/3, Chroma offers a separate f/2.8–f/3.6-optimised version.
Specifications
Chroma part number
27006 OIII 3nm Bandpass
Target line
OIII, 500.7 nm
Bandwidth
3 nm
Format
2-inch M48 threaded ring
Coating
Hard sputtered; AR-coated back face
Substrate
Single glass substrate; 3 mm thick (Chroma astronomy brochure)
Chroma OIII 3 nm 2" (27006) — ultra-narrowband, M48 threaded ring The Chroma 27006 OIII 3 nm bandpass filter isolates the 500.7 nm primary emission line of doubly ionised oxygen, the next most common nebular emission after H-alpha. Its ultra-narrow 3 nm passband gives maximum contrast and background suppression, ideal under light-polluted skies or bright…
Manufacturer model: Chroma 27006 OIII 3nm, 2-inch M48 threaded ring · Specifications checked against manufacturer data on 2026-11-03
