IDAS NB3 Contrast Boost Dual Line-Pass Filter The NB3 filter is a dual line-pass filter which can be used with one-shot color (OSC) cameras such as DSLR's or astronomical OSC cameras. Passing the red SII and the blue-green OIII lines, the NB3 filter enhances the contrast of these lines found in emission nebulae without the time-consuming use of single-band filters. The resulting images can be used for luminance contrast enhancement of traditional RGB-balanced images or creation of images in various popular false-color palettes. Note that a base filter which provides IR blocking is required in combination with this filter (see example at right). NB3 Filter (with NGS filter to block IR) Band-pass Plot -- Click to enlarge NB3/NGS filtered image example. The NGS filter provides the IR blocking required for using the NB3 filter. Click to enlarge Veil Nebula - NB2/NB3 combined final image. Click to enlarge Additional example: M8/M20 region in the DigiBorg blog. NB Filter Types Emission Lines Filter Sizes Base Filter NB1 Triple - Hβ+OIII, Hα 48mm & 52mm None required NB2 Dual - OIII, Hα 48mm, 52mm, Canon Drop-in Required* NB3 Dual - OIII, SII 48mm, 52mm, Canon Drop-in Required* * In-camera IR blocker works as the base filter.
