Antlia SHO 3nm Pro Highspeed filters
Optimized for high-speed systems (f/2.6 to f/3.6)
Antlia's SHO 3nm Pro Highspeed filters are optimized for fast-focus systems thanks to a pre-shift of the center wavelength (CWL). This specially designed version significantly improves the signal-to-noise ratio (SNR) on telescopes with focal ratios between f/2.6 and f/3.6, compared with the standard Pro 3nm versions.
In fast optical systems, the light path forms a cone with increasing angle of incidence, shifting the CWL towards the blue. At f/2.6, an angle of 10° results in a blue shift of 2.2nm. High-speed filters are therefore pre-shifted by 1.2nm towards the red to compensate for this effect and ensure optimum signal acquisition.
Comparison and recommendations
- For f/2.6 to f/3.6: use 3nm Pro Highspeed filters
- For f/>3.6: prefer standard 3nm Pro filters or Ultra 2.5nm filters
- For f/<2.6: use EDGE 4.5nm filters
Performance and applications
- High transmission (>90%) and 3nm bandwidth for maximum contrast
- Designed for f/2.6 to f/3.6 systems
- Clean spectral profile to reduce halos around bright stars
- OD5 out-of-band rejection (0.001%) to minimize light interference
- One-piece substrate to eliminate internal reflections
- Target objects: emission nebulae, planetary nebulae, Wolf-Rayet, supernova remnants
- Suitable for polluted skies and dark sites
- Imaging even with the Moon
- Blackened edges for unmounted filters
- Superior optical reliability reduces post-processing
Technical specifications
| Parameter |
H-alpha |
OIII |
SII |
| FWHM |
3nm |
3nm |
3nm |
| Center wavelength (CWL) |
657.5nm |
501.9nm |
673.6nm |
| Max. transmission |
90% |
90% |
90% |
| Out-of-band discharge |
≥OD5 @ 300-1000nm |
| Thickness |
2mm ±0.05mm (except Ø50mm: 3mm ±0.05mm) |
Optical quality
- Substrate: unglued single-piece optical glass
- Surface quality: S/D = 60/40 (MIL-O-13830 standard)
- Transmitted wavefront: λ/4 or better
- Parallelism: < 30 arcsec
- 3-year warranty against delamination
Filter mount
- Antlia standard: 1.25'' (M28.5×0.6), 2'' (M48x0.75)
- Ultra-thin cell for reduced vignetting
- Black anodized finish
- Tamper-proof laser engraving
Spectral shift curves (blueshift)
Spectral curves
Not recommended for :
- Solar observation
- Visual observation at night
Warning
NEVER LOOK AT THE SUN WITH THIS FILTER. This will result in serious eye damage.
