Extreme light pollution reduction Ultra narrow 3nm bandpasses Isolates key H-alpha and OIII emissions Provides superior contrast and a darker sky background Minimizes star halos on bright stars Description Specifications In the Box Optolong L-Ultimate Overview The Optolong L-Ultimate is a high-performance dual-bandpass filter explicitly designed for astrophotographers who use color cameras (DSLR, CMOS, or CCD) to capture emission nebulae. With its ultra-narrow 3 nm bandpasses centered on the key nebula emission lines— O III at 500.7 nm and H-alpha at 656.3 nm —the filter lets through only nebular light and blocks all unwanted street lights and atmospheric emissions. This dramatically darkens the sky background and significantly enhances image contrast and signal-to-noise ratio. The L-Ultimate is one of the most effective tools available for cutting through extreme light pollution to capture stunning images of emission nebulae. One-Stack Dual Wavelength Capture Unlike monochrome setups that require multiple filters and long exposure nights, this filter captures both H-alpha and OIII signals in a single exposure when paired with color cameras. This saves you time and simplifies your setup, allowing you to achieve results rivaling those from a monochrome camera with separate narrowband filters. Sharper Stars, Minimal Halo Effects The L-Ultimate is engineered to greatly reduce halos around bright stars —a common issue with wider band filters—offering crisper, cleaner stars in your images. By blocking out all light except for the critical H-alpha and OIII emission lines with ultra narrow 3nm bandpasses, the filter maximizes the signal from the nebulae while minimizing the noise from the sky background, leading to a cleaner final image that requires less post-processing. L-Ultimate vs. L-eNhance & L-eXtreme The L-Ultimate is a dual 3 nm ultra-narrowband filter that transmits only the H-alpha (656.3 nm) and O III (500.7 nm) emission lines. Compared to the L-eXtreme (dual 7 nm) and L-eNhance (H-alpha 10 nm + O III/H-beta 24 nm), the L-Ultimate offers several advantages: Darker sky background – its tighter 3 nm bandpass blocks nearly all light pollution and unwanted wavelengths. Higher contrast and finer details – faint nebular structures stand out more clearly. Superior star control – greatly reduces halos and star bloat compared to the L-eXtreme and especially the L-eNhance. Optimized color preservation – maintains the natural balance of H-alpha reds and O III blues/greens. In short: L-eNhance – entry-level light pollution filter, wider bandpasses, captures more broadband light but with more sky glow. L-eXtreme – tighter control (7 nm), stronger light pollution reduction, but still allows more background light than the L-Ultimate. L-Ultimate – most advanced option, with the narrowest bandpass for maximum contrast, cleanest stars, and the best performance in heavy light pollution or under bright moonlight. UV and IR Blocking The L-Ultimate filter's design inherently suppresses ultraviolet (UV) and infrared (IR) wavelengths. This feature simplifies the imaging workflow by eliminating the need for a separate IR-cut filter. This comprehensive blocking capability ensures that extraneous light from both ends of the visible spectrum does not interfere with the final image. Material Schott B270 optical glass Thickness 1.85mm Filter Cell Height 4.8mm without male thread, 6.8mm with thread FWHM H-alpha 3nm, OIII 3nm Surface Quality 60/40 (Refer to MIL-O-13830) Optical Polish Fine-optically polished to ensure accurate 1/4 wavefront and < 30 seconds parallelism Transmission High transmission at H-alpha (656.3nm) and OIII (500.7nm) Blocking OD4 (300-1000nm), blocking all major artificial light pollution lines L-Ultimate filter × 1 Plastic Filter Case × 1
