Antlia 3nm Pro H-alpha filter
Antlia's 3nm H-alpha Pro filter optimizes bandwidth to 3nm FWHM. This very narrow band enhances the contrast of emitting targets by reducing unwanted background signals. This filter guarantees 88% transmission at H-alpha wavelength (656.3nm), providing maximum signal and excellent definition of nebulous structures.
Unlike wider filters, this filter strongly limits losses due to center wavelength shifts (CWL). It guarantees transmission greater than 88% within a range of ±1nm around the center band, enabling it to be used with both slow and fast lenses (up to f/3) without significant signal loss.
Out-of-band rejection is rated OD5 (0.001%), ensuring an excellent signal-to-noise ratio and effectively blocking interference. The sharp spectrum cut-off also reduces halos around bright stars.
Application and performance
- High transmission and narrow bandwidth for maximum contrast
- Steep spectral profile to limit halos
- Unique substrate to eliminate internal reflections
- Target objects: H-alpha nebulae, planetary nebulae, Wolf-Rayet nebulae, supernova remnants
- Can be used on polluted sites or in dark skies
- Extends imaging time even with the Moon present
- Compatible up to f/3 without significant signal loss
- Blackened edges to reduce glare on unmounted models
- Superior optical reliability to minimize post-photo processing
- Specially designed for deep-sky objects containing H-alpha
Technical specifications
| Parameter |
Value |
| Substrate |
Optics, unglued monoblock |
| Filter thickness |
2mm ±0.05mm (1.25″, 2″, 31mm, 36mm), 3mm ±0.05mm (50mm, 50x50mm) |
| FWHM |
3nm |
| Center wavelength (CWL) |
656.3nm |
| Maximum transmission |
>88% |
| Out-of-band discharge |
OD5 (0.001%) from 300 to 1000nm |
| Surface quality |
S/D 60/40 (MIL-O-13830 standard) |
| Transmitted wavefront |
λ/4 or better |
| Parallelism |
< 30 arcsec |
| Warranty |
3 years against delamination |
Spectral curve
Mounting ring
- 1.25'' (M28.5×0.6), 2'' (M48x0.75)
- Ultra-fine cell to reduce vignetting
- Black anodized finish, unalterable laser engraving
Major nebula emission lines
- H-α : 656.3nm
- H-β : 486.1nm
- OIII: 495.9nm and 500.7nm
Available sizes
- Mounted: 1.25″, 2″
- Unmounted: Ø31mm, Ø36mm, Ø50mm, square 50x50mm
Not recommended for :
- Solar observation
- Visual observation at night
Warning:
NEVER LOOK AT THE SUN WITH THIS FILTER. Serious eye damage may occur.
