The Baader Planetarium LRGBC CCD Filter Set delivers improved color separation and image quality without annoying halos. Baader has created excellent CCD filters through an extensive coating-stack design and testing program. Baader has partnered with the world's leading thin film coating company to produce transmission curves that border on the ideal. Simply put - Baader's LRGBC anti-reflection filters deliver improved images for your astrophotography! Unfortunately, their obvious improvements will likely cause many astro-imagers to re-take images of their favorite objects. This set contains five round 36 mm unmounted filters: one each of red, green, and blue colors, plus a UV/IR-Cut filter (luminance), and one Clear precision-polished filter. Each of the LRGBC 36 mm filters are 2 mm thick.
Their ultra steep cutoffs and high transmission, >95% allows Baader to achieve something no other RGB filter set has - they are able to effectively separate the important H-Beta and O-III lines. The Baader Blue filter passes virtually all of the H-Beta lines, while the Green filter is able to capture all of the O-III line, without encroaching into the H-Beta line. None of the light is wasted by either filter. In this way, O-III is represented as it should be, a teal (blue-green) color, and H-Beta is captured solely in the blue. This novel degree of separation is achieved, along with high transmission for both lines. In addition, the Green and Red filter passbands nearly touch, leaving only a sharp notch to block out the primary Mercury/Sodium light pollution line at 580 nm. The high transmission everywhere else delivers the shortest combined exposures possible with every detector.
The high optical quality of the Baader narrowband filters guarantees no loss in sharpness or contrast. Each substrate is fine-optically polished plane parallel to deliver a smooth and accurate 1/4 wavefront over the entire surface. Each filter is blocked and polished individually, not cut out of a larger plate of glass. The special custom polishing operation sets Baader filters apart from other filter manufacturers.
Coatings are professionally applied to each Baader CCD filter by the most sophisticated equipment available today, ensuring high consistency for bandpass cutoffs, transmission, and out of band blocking. The anti-reflection coatings are evenly balanced on both sides of the filters to reduce surface stresses and prevent deformation of the substrates. The ultra-hard ion beam deposition ensures the coatings will never degrade from use or normal cleaning. Baader coats each LRGBC filter individually. Baader filters remain sealed at their coating edges for a long life without degradation. Though more costly, this process avoids coating failures resulting when filters are "biscuit cut" from bulk-coated sheet glass, leaving ragged edges for moisture to penetrate, and cause coatings to peel. Baader filters are intended for a lifetime of real-world use!