Ligh pollution reduction filter Keeps natural color balance to your images Effective for use in heavy light-polluted areas Suitable for visual and photographic use Description Specifications In the Box Optolong L-Pro Overview The Optolong L-Pro filter is one of the most versatile light pollution filters available for astrophotography and visual observing. Designed with advanced multi-bandpass technology, it selectively reduces the effects of artificial lighting, such as mercury and sodium vapor lamps, while preserving the natural colors of stars and deep-sky objects. Unlike aggressive narrowband filters that limit your target selection, the L-Pro strikes a careful balance: it suppresses unwanted light without compromising true-to-life color For astrophotographers shooting from areas affected by moderate to heavy light pollution, the Optolong L-Pro is often one of the first filters we recommend. It provides a noticeable improvement in contrast and detail without the trade-offs of unnatural color shifts. Whether you are imaging galaxies in broadband or capturing emission nebulae, the L-Pro delivers consistent, high-quality results. Light Pollution Suppression The L-Pro filter achieves its effectiveness by selectively reducing the transmission of specific wavelengths associated with artificial light pollution, including mercury vapor, high-pressure, and low-pressure sodium vapor lamps. Additionally, it attenuates the unwanted natural light caused by neutral oxygen emission, which is the source of night skyglow. Concurrently, the L-Pro filter maintains high transparency at the major nebula emission lines: H-alpha (656nm), OIII (496nm and 500nm), H-beta (486nm), and SII (672nm). This precise transmission profile enhances contrast and detail, making the filter suitable for high-end imaging and visual applications in sub-rural and urban environments. True Color Balance A key attribute of the Optolong L-Pro is its balanced transmission profile. The filter has a very low transmission reduction rate for broadband celestial objects. This property makes it exceptionally effective in suppressing light pollution without significantly impacting the natural spectral characteristics of objects like galaxies and reflection nebulae. This is a crucial feature for astrophotography requiring faithful color reproduction, ensuring that images maintain their natural appearance with minimal post-processing. UV and IR Blocking The L-Pro 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, allowing it to be used for "L" (luminance) channel imaging with CMOS cameras. This comprehensive blocking capability ensures that extraneous light from both ends of the visible spectrum does not interfere with the final image. For Imaging & Visual Use While optimized for astrophotography, the L-Pro also benefits visual observers, offering darker backgrounds and improved contrast when viewing under urban or suburban skies. Available as clip-in filters for DSLR and mirrorless cameras Available in popular sizes (1.25", 2", and clip-in formats for DSLR cameras), it integrates seamlessly with telescopes, refractors, and camera lenses. Clip-in Options Canon EOS APS-C Canon EOS Full Frame Canon EOS R* Nikon Full Frame Sony Full Frame *Due to the particularity of Canon R cameras, vertical dark bands on both edges may occur when using an interference filter for imaging. You may need to crop the image, or correct it our in post processing. Material Schott B270 optical glass Thickness Screw-on filters: 2.0mm Clip-in filters: 1.0mm Filter Cell Height (1.25" and 2" versions) 4.8mm without male thread, 6.8mm with thread Spectrum 380-750nm 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 major nebula emission lines: H-alpha (656nm), OIII (496nm & 500nm), SII (672nm), and H-beta (486nm) Blocking Precision off-band blocking of major artificial light pollution emission lines: Na (589nm), Hg (435nm & 578nm) L-Pro filter × 1 Plastic Filter Case × 1
