Optolong Hydrogen-Alpha 7nm Filter

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H-Alpha 7nm filter is the most popular narrowband filter, allowing 7nm bandwidth of light centered on a wavelength of 656nm through. It reduces the transmission of certain waveleng ths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. sky glow). This is the best choice of narrowband H-alpha astrophotography filter for highest contrast and revealing subtle nebula details. Fine-optically polishing for double-sides-- Ensure accurate λ/4 wavefront and Show more