The OIII CCD 12nm filter is designed to let pass only the O-III line at 501nm, one of the wavelengths emitted by the planetary nebula and some emission nebulae. Due to the very narrow band, this filter generates a high contrast with the complete removal of light pollution making long exposure astrophotography possible also suburban places. The filter O-III CCD 12nm is also perfect for use with monochrome CCD cameras to record color pictures together with the H-alpha and SII narrow-band filters.
The filters are always available in two diameters: 31.8mm and 50.8mm. These standards are commonly used by telescopes and their accessories. For example, depending on their function, they can be used with a CCD ora A DSLR camera (using appropriate photo adapters), but also screwed to optical accessories such as eyepieces or diagonals. Warning: 31.8mm filters do not work with 50.8mm diameter accessories and vice versa (unless there are special adapters). When you choose the version of your filter, be careful to choose the diameter compatible with your equipment.
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