ALP-T Dual Band 3nm SII&OIII Filter - 2'' Mounted

The Antlia ALP-T Dual Band 3nm SII&OIII is a narrowband astronomy filter designed to isolate the Sulfur-II (672.4 nm) and Oxygen-III (500.7 nm) emission lines. It is intended primarily for use with colour (OSC) cameras to increase signal-to-noise and contrast when imaging emission nebulae.

Key optical characteristics

The filter uses an ultra-narrow 3 nm full-width at half-maximum (FWHM) bandpass at each targeted wavelength to concentrate on the SII and OIII lines while strongly suppressing out-of-band light. Antlia’s multi-layer, double-sided coating process and anti-reflective treatments are applied to a polished optical substrate.

Practical use notes

• Optimised for astrophotography with colour cameras; can also be used with monochrome cameras as a luminance-saving option.
• Blocking to high optical density helps reduce the effects of light pollution, moonlight and airglow for improved nebula contrast.
• Recommended for use with optical systems at or slower than f/4; Antlia offers alternative pre-shifted high-speed versions for faster optics.
• Not for solar observation. Do not use to view the Sun.

Compatibility and mechanical

This listing is for the 2" mounted version with an M48 x 0.75 filter thread.

Note: The product page supplied detailed optical performance numbers and manufacturing process descriptions. Where package contents or any additional included accessories were not explicitly listed on the source page, those items are not stated here.