IDAS LPS-D3 Light Pollution Filter

The IDAS LPS-D3 (formerly NGS1 and D2) filters enhance the contrast of astronomical emission nebulae against a sky with both man-made and natural* sky glow sources, yet preserve the colour balance of broadband objects such as galaxies. As with other IDAS interference filters, the bandpasses are designed to accommodate the steep ray angles of fast optical systems.

Light pollution suppression (LPS) filters are designed to suppress the common emission lines generated by artificial lighting, yet allow the important nebula emission lines to pass, thus enhancing the contrast of astronomical objects, particularly emission nebulae (see filter plots). The most recently introduced version (D3) has a bandpass designed to cope with the increasing trend of society's switch to LED lighting.

Unlike other light pollution suppression filters, IDAS filters are specifically designed for balanced colour transmission using the IDAS unique Multi-Bandpass Technology (MBT) process. The balanced transmission allows colour photographs to be taken with minimal colour cast to broadband emission objects such as stars, galaxies and globular clusters.

LPS filters utilise the unique IDAS Ion Gun Assisted Deposition (IGAD*) coating technology for superior coating durability (quartz hardness) and safer cleaning. IGAD coatings also improve temperature and humidity stability of the filter performance, reducing spectrum shifts down to +/-1nm from the +/-3 or 4nm shift of standard coatings.