Dual Narrowband Astronomical Filters are used for:

Deep-sky Imaging: Isolate specific emission lines (e.g., Ha at 656nm and OIII at 500.7nm) to capture detailed structures of emission nebulae and planetary nebulae.

Light Pollution Reduction: Block unwanted light, enhancing visibility of faint celestial objects in urban areas.

Improved Contrast: Make dark regions of nebulae and galaxies stand out.

Long-exposure Photography: Allow extended exposure without overwhelming noise.