H-Alpha 7nm filter is the most popular narrowband filter allowing  7nm bandpass of light centered on a wavelength of 656nm. Extra narrowband SII-CCD 6.5nm and The OIII-CCD 6.5nm  filters  are designed for nebula observation allowing 6.5nm bandpass  of light centered on a wavelength of 500nm (Oxygen-III) and 672nm (Sulfur-II) through, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow)

• For tricolor CCD astrophotography
• Narrowband imaging with SHO set can be done with the moon up in heavy light pollution, so your equipment is not sitting dormant for several weeks
• Hubble look of images can be made by the combination of H-alpha, OIII-CCD, and SII-CCD, such as the famous “Pillars of Creation” (M16 Eagle Nebula)

• H-alpha Filter
• SII Filter
• OIII Filter