Description
The 1.25" ZWO Duo-Band Filter passes light in the hydrogen-alpha (656.3nm) and O-III (500.7nm) wavelengths. It improves contrast and seeing for deep space objects such as emission nebulae, and can be used to filter out moonlight or urban light pollution. With a one-shot color astronomy camera, it allows use of narrowband techniques that normally require a monochrome camera, filter wheel, and narrowband filters. The Schott-substrate glass is 1.85mm thick, optical-coated on both sides, and mounted in machined metal with engraved lettering.