SV220 H-Alpha 3nm and O-III 3nm Ultra Dual-Narrowband Filter enhances astrophotography by reducing stray light and light pollution, enhancing image clarity, suitable for capturing deep-sky objects. Full-frame design ensures no vignetting, broad field of view, and accurate color reproduction. It improves image uniformity, clarity, and contrast, ideal for high-res deep-sky observations, maintaining consistent quality across the frame. SV555 APO Telescope (54mm refractor, Petzval objective structure) pairs with SV226 Telescope Filter Drawer; both tailored for deep sky astrophotography. The telescope delivers sharp cosmic details via its optimized optics & variable aperture; filter drawer refines light for better celestial imaging. All initial issue resolved; we have fully UPGRATED through hardware enhancements&process; All current and future batch deliver reliable performance for seamless user experience.1.Enhanced Focus Precision for crisp star; 2.Weight Reduce 90g+ for travel astronomy;3.Optimized Lens Hood-full protection. SV226 filter drawer adopts integrated CNC molding and anti-light leaking design. It can compatible with 1.25" & 2" specifications filters on the market. Strong magnetic attraction, prevent the filter from falling off. The threads on both sides of the SV226 filter drawer are M48x0.75 internal threads and M42x0.75 external threads, which are compatible with most specifications of astronomical cameras. Note: If you want to connect with a dslr camera, you need to use an additional camera adapter.