The 1.25-inch O-III filter is useful for larger telescopes where the light from the Moon can be extremely dazzling. It brings out details on darker objects like nebulae. It only allows the double ionization lines of oxygen between 495.9 nm and 500.7 nm to pass through with an efficiency of 90%.

Features

• Size: 1.25 inches (18nm)
• Blocking range: 400-700nm
• Transmittance: 90% at 495.9nm and 500.7nm
• FWHM: 18±2nm
• Thickness: 1.85mm

Benefits

This filter is designed to enhance contrast when visually observing gaseous and planetary nebulae in all sky conditions. It provides a high-contrast image even in areas with significant light pollution.

The filter is made from high-quality glass with dichroic and anti-reflection coatings, making it useful not only in light-polluted areas but also for increasing contrast in dark sites.

Usage

This filter can be used with all 1.25-inch eyepieces. It is designed to block nearly all other visible wavelengths, optimizing the view of nebulae.