Vaonis Vespera Dual-Band FilterThe Vespera Dual Band Filter is a dual narrowband interference filter that will significantly improve your photo quality whether you are viewing from an urban or natural environment. By selecting very precisely the wavelengths of Hydrogen Alpha (H alpha) and Oxygen III (O III), found mainly in nebulae, the filter will increase the contrast between the Stellar object and the sky background. Thus, its use makes it possible to obtain a higher quality