The Baader H-Alpha 7 nm diplex filter (6562.8 ?) allows images of the H-II regions with the highest contrast to be obtained with the shortest possible exposure times. Its narrow band in the H-Alpha region has a transmission rate of over 90%. At the same time, it completely eliminates light pollution with anthropogenic light. The filter has been extremely precisely ground so that the surfaces are perfectly parallel and accurate to 1/4 the length of the wave over the entire surface. Multilayer dielectric coatings applied plasma and ionically cured are exceptionally hard and durable. The coatings in this filter are not damaged during normal use and cleaning.
(measurements on the Varian Cary 100 spectrophotometer, July 2015)