Astronomik O-III Visual Filter

This filter is designed specifically for gaseous and planetary nebulae. By isolating the O-III emission lines, it significantly increases the contrast of these objects against the background sky, making faint details visible that would otherwise be washed out.

This 1.25-inch filter is compatible with telescopes 6 inches (150mm) and larger. It is optimized for aperture ratios between 1:3.5 and 1:15, making it a versatile choice for most standard visual setups.

Yes, it effectively blocks light pollution caused by sodium and mercury vapor lamps. While it won't eliminate all forms of sky glow, it is highly effective at suppressing the most common types of artificial street lighting.

A parfocal design means that once you have focused your telescope, you won't need to refocus when you swap this filter in or out. It saves you time and frustration during observation sessions by maintaining your focus point across different optical components.

The 12nm Full-Width-Half Maximum (FWHM) provides a precise balance between high contrast and image brightness. It is narrow enough to block unwanted light pollution effectively while still allowing enough light through to keep the nebula visible and detailed.