Astronomik OIII visual 2" — for planetary nebulae and supernova remnants The Astronomik OIII visual filter has a narrow passband around both OIII lines, giving a large contrast gain on gaseous and planetary nebulae. It blocks sodium and mercury-vapour lamp lines and natural airglow, so it works well under both light-polluted and dark skies.
Manufacturer model: Astronomik OIII visual 2" (M48), 10211200 · Specifications checked against manufacturer data on 2026-11-03
The Astronomik OIII visual filter has a narrow passband around both OIII lines, giving a large contrast gain on gaseous and planetary nebulae. It blocks sodium and mercury-vapour lamp lines and natural airglow, so it works well under both light-polluted and dark skies.
By passing the 496 nm and 501 nm OIII lines with high transmission, the filter can reveal faint supernova remnants and planetary-nebula detail that is otherwise hard to see. Astronomik rates it very good for visual use under both dark and urban skies.
The filter suits focal ratios from f/3.5 to f/15 and works best with telescopes from 6 inches (150 mm) aperture upwards.
| Lines | OIII, 496 nm and 501 nm |
|---|---|
| Typical transmission | 95% at 496 nm and 501 nm |
| Transmission range | 494–506 nm |
| Bandwidth (FWHM) | 12 nm |
| Focal ratio range | f/3.5 to f/15 |
| Recommended aperture | 6 inches (150 mm) or larger |
| Manufacturer code | 10211200 |
|---|---|
| Format | 2-inch cell, M48 × 0.75 thread |
| Glass thickness | 1 mm |
| Coating | Astronomik MFR |
| Made in | Germany |
Astronomik OIII visual 2" product page
OIII visual (12 nm, 10211200), not the OIII 12/6/4 nm narrowband imaging filters.
| Transmission range (nm) | 494–506 |
|---|---|
| Recommended aperture | 6 in (150 mm) or larger |
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Astronomik OIII visual 2" — for planetary nebulae and supernova remnants The Astronomik OIII visual filter has a narrow passband around both OIII lines, giving a large contrast gain on gaseous and planetary nebulae. It blocks sodium and mercury-vapour lamp lines and natural airglow, so it works well under both light-polluted and dark skies.
Manufacturer model: Astronomik OIII visual 2" (M48), 10211200 · Specifications checked against manufacturer data on 2026-11-03
