iOptron 1.25″ Filters H-alpha: H-alpha narrowband filter of 7 nm
This narrowband filter transmits only the deep red light of the H-alpha emission line around 656 nm, the wavelength at which hydrogen nebulae glow most brightly. Structures and faint outer extensions that get drowned out in broadband are brought into sharp focus with this.
The 7 nm full-width at half-maximum blocks almost all other light, including light pollution and moonlight. As a result, H-alpha can be photographed well even from the city and with the Moon in the sky.

Building block of narrowband palettes
H-alpha is the basis of every narrowband palette: as the red channel in HOO or as the green channel in the Hubble palette SHO. The 1.25-inch aluminum cell fits into standard filter wheels.
Included
- H-alpha filter, 1.25″ mounted
Featured accessories
Combine with iOptron's OIII and SII filters for the full Hubble palette.
For whom yes and for whom no
- Monochrome emission nebula photographers, even from light-polluted areas
- ✗ Visual observers and color cameras without dual bandpass: this filter is not intended for them
Specifications
| Emission line | H-alpha, 656 nm |
| Half-value width | 7 nm |
| Format | 1.25-inch aluminum vatting |
| Observation goals | Narrowband photography with monochrome cameras |
You can find more mounts and accessories for this brand at the iOptron brand page.





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