Baader Filters OIII CMOS f/2 Ultra-Highspeed 31mm

The OIII filter exclusively permits light with a wavelength of 501 nanometers, corresponding to the spectral lines of doubly ionized oxygen. These lines are emitted by planetary and some emission nebulae, allowing these celestial objects to remain visible while other wavelengths are filtered out. This selective filtration enhances contrast, revealing faint nebulae that were previously invisible.

In astrophotography, these filters are most effective when paired with monochrome cameras. For optimal results, images captured with OIII filters should be combined with those taken using H-alpha and SII filters. This composite image presents faint nebulae with enhanced clarity and stark contrast.

Specifications:

Capacity: Central wavelength of 500.7 nm with a half-value width of 4 nm

Frame: Ring, constructed from aluminum

Optical System Coating: Reflex-Blocker™

Suitable for apertures ranging from f/3.4 to f/1.8

Filter thickness: 2 mm

Filter size: 31 mm

General: Line filter categorized under the f/2 Ultra-Highspeed series

Area of Application: Useful for nebulae and galaxies in photographs, not visually for direct observation, not suitable for twin stars, moon, or planets.