The filter improves the color and contrast of the observed objects, and also has the property of the Light Pollution filter, reducing the effect of street lighting on the observed images of the sky. This filter darkens the sky background, but strengthens the constituent red, green and blue. This filter also reduces the exposure of the sky and the decrease in contrast caused by the presence of the Moon in the sky during observation. It works great in combination with the Fringe Killer filter. It is characterized by excellent quality of performance - the filter surfaces are mutually parallel and deviations from the parallelism do not exceed ? 30 arcary angles in any place. The coatings are resistant to scratches and scratches.
(measurements on the Varian Cary 100 spectrophotometer, July 2015)
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