Filtre Duo-Band Sky Watcher 31,75mm

In order to limit light pollution, a real plague in visual and even more so for astrophotography, ZWO offers a "2-in-1" filter: the Duo-Band! The idea is simple and consists of combining 2 filtrations: one around the H-Alpha line and the other around the O-III lines. Thanks to multiple layers of high reflectivity treatments, transmission in these 2 characteristic emission peaks of nebulae reaches a minimum of 90%.

This ZWO Duo-Band filter is compatible with APN (pre-dewarped), CMOS and CCD color cameras (One Shoot Color) which generally have good sensitivity in the O-III and H-Alpha lines. It's an interesting alternative to the combination: "monochrome camera + filter wheel + 3 narrowband filters". It allows you to reject a large part of the light pollution emitted by mercury, sodium, LED lamps.

The aluminum cell is manufactured by CNC machines which impose great precision in manufacturing. Available with diameters 31.75 and 50.8mm

ATTENTION: The incident radiation must arrive perpendicularly to the filter, otherwise it will degrade the performance of the filter. The maximum angle should be 8°, so the ZWO Duo-Band filter is not compatible with large and ultra-wide-angle objectives.