Antlia S-II Pro Ultra Filter - 2.5 nm Ultra Narrowband - 36 mm diameter unmounted

Antlia ultra narrowband filter with 2.5 nm bandwidth

Antlia nebula filters offer extreme contrast. Thus, the astrophotographer achieves a very good result even with considerable stray light from cities or from the moon. This makes the narrowband filters interesting also for fast telescopes and objectives. Even at an extreme focal ratio of f/3.5, there is only minimal transmission loss.

The Antlia SHO 2.5nm Ultra series filters use Ohara quartz glass and are manufactured under precisely controlled coating processes. The Ultra series are optimized with a FWHM (full width half maximum) of 2.8 nm +/-0.5 nm and a transmission efficiency >95-97% at the emission wavelength. The result is a very high Signal to Noise Ratio.

The Ohara quartz glass has an ultra-low thermal expansion coefficient with outstanding thermal and mechanical properties. When these superior glass characteristics are combined with advanced coating processes, these filters will provide excellent durability for imaging and research in the toughest environmental conditions.

All the 2.5nm Ultra filters are 100% scanned individually, all transmission and blocking (OD) data in the box are actual, measured spectra.

Compared with 3nm Pro series, 2.5nm Ultra series coated on Ohara quartz glass and showed higher transmittance Ha/SII >97%, OIII >95%. It is estimated that these filters will provide 20-30% signal improvement in your images as compared to the 3nm Pro series. In addition, the Ultra series has a 10% narrower FWHM of 2.5 nm +/-0.5 nm. The Ultra series narrowband filters will allow you to capture improved contrast and structural detail.

The main features and application:

High transmittance (Ha/SII >97%, OIII >95%) and the narrowest FWHM of 2.5 nm +/-0.5 nm to maximize contrast;

Flat-top spectrum minimizes the loss in transmission due to the Center Wavelength (CWL)-shift;

Out of band blocking specification is designed to OD5 (0.001%) to block interference from other wavelengths and minimize halos around bright stars;

Made of Ohara quartz glass, excellent durability and thermal stability, better fracture resistance and scratch resistance, improved coating resilience to cleaning;

Identical filter thickness to existing standards and double-sided fine polishing , with utmost care for parfocality

SHO 2.5nm Ultra filters can be used down to f/3.5 systems with minimal loss of signal. (This does not mean that optics with faster focal ratios will not be applicable, the flat-top design reduce the effect of wavelength shift and you can still use the 2.5nm Ultra narrowband);

100% of production are scanned individually, all transmission and blocking (OD) data in the box are actual, measured spectra and transmission;

All Antlia filters are coated to the edge of the substrate and unmounted narrowband filters are edge blackened to eliminate internal reflections from stray light;

Warranty: 3-years against delamination

Question:
Do I have to pay attention to the orientation of the filter when installing it??

Answer from Teleskop-Service:
The installation direction of the filter does not affect the imaging result of deep sky photography. This is because both sides are coated to improve transmission rate and cut-off data, and it is no longer necessary to determine which side faces the cameras for optimal performance.

Safety informations: PDF Download