Cytron Japan Quad BP Filter III bandpass 48mm (quad filter)

The conventional QBP filter was designed to gradually transmit near-infrared rays of 900 nm or more, but when used in conjunction with an achromat mirror, a phenomenon was observed in which bright stars were wrapped in a halo. By extending the wavelength range to be cut to 1,100nm, this product suppresses the appearance of halos around bright stars when used in conjunction with an achromatic mirror. By mainly transmitting wavelengths near the four main emission lines (Hα, Hβ, OIII, and SII) emitted by celestial bodies, and cutting out other wavelengths, the nebula can be seen even in light-polluted areas. Filter size: 48mm Thread diameter: 48mm Thread pitch: 0.75mm Filter thickness: 1.5mm