Antlia 3nm Pro Highspeed H-alpha filter

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

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.