Altair 2" DualBand 4nm COMBO(2 Filters)

Altair Dual-Band ULTRA Oiii / Sii narrowband filter with extremely tight 4nm FWHM Bandpass. This filter is designed to be the perfect complement to the Altair 4nm Ha Oiii filter. By using both filters you get twice the Oiii data you would otherwise - so you can now do proper Hubble pallette style imaging with a colour camera! DualBand Sii Oii DualBand Ha Oiii Ha N Y Sii  Y N Oiii Y Y 2x the Oiii Data when used together! This filter delivers what most consider to be the perfect balance of flexibility and transmission. What's more it delivers 90% transmission over both wavelengths in the same filter, due to a special coating process. For imaging in moonlight and extreme light pollution as in a major city, with a colour CMOS camera - or even in dark conditions if you want total control over your channels. The filter transmits only the Sii and Oiii light from emission nebulae, with almost total suppression of unwanted light, with OD4/5 (0.01%~0.001%) over the majority