Altair Quad-Band 2" Filter for OSC CMOS, CCD and Modified DSLR cameras.
Narrowband Bi-Colour imaging is a growing new trend in astrophotography, especially popular in light polluted areas, or for imaging in rural areas in moonlight.
Now you can capture the two main emission nebulae bands at the same time, whilst suppressing light pollution, moonlight, and airglow. Capture more data in less time, and open up your imaging time window - even into the summer months.
Altair Tri-Band and Quad Band filters work by isolating the primary nebulae emission zones in the red and blue/green wavelengths, and separating them into two main "zones" with a wide separation for easy capture with a colour camera - all in one exposure! Not only is capture very convenient, but processing is easy too, thanks to the wide separation of the green/blue and red "zones". Light pollution control is extremely effective and LED light is also significantly reduced, thanks to the effects of Rayleigh scattering.
There are two types of filter:
Tri-Band - combines Ha into a red zone, and H-beta + Oiii into a green/blue zone. (Recommended for high to severe light pollution).
Quad Band - combines Sii AND Ha into a red zone, and H-beta + Oiii into a green/blue zone. (Recommended for moderate light pollution).
Sensitive OSC or "One Shot Colour" CMOS cameras like the #Hypercam183C capture these wavelengths very efficiently, and allow them through the Bayer matrix. The filters also work with DSLRs (APS-C sensor size modified cameras are best, but normal ones will also work). When you have the complete stack of exposures, processing is relatively easy because of the large separation in colour. You can also use the Quad band and Tri-Band filters as a "super luminance filter" for imaging nebulae with Mono cameras.
Quad-band OSC filter CWL:
1st band, CWL495nm FWHM35nm
2nd band, CWL 660nm FWHM 35nm
1mm thick optical glass with 30 arc sec parallelism.
UVIR Block and Anti-Reflection Coating.