Baader Planetarium 2 Inch Dark Blue Eyepiece Filter

Description

Freedom from Ghost images, even when stacked.  Striae-free substrates are polished parallel to 30 seconds of to avoid wedge errors.  Finest 7-layer  hard multicoatings on both faces feature 0.25% residual reflections (Baader filters are unique, no other colored filter incorporates anti-reflection multicoatings).  The coatings are also different for each of the filters, in order to match the coating performance to the filter curve of each color.  This maximizes the transmission and minimizes reflections.

Extremely High Transmissions result in maximum contrast and isolation of planetary details, even with smaller telescopes.  Efficiencies of the three longpass filters (Red, Orange, and Yellow) peaks at 98%, and efficiencies of the three bandpass filters (Green, Blue, Dark Blue) achieve 70%. 

Carefully designed spectral characteristics.  Filters may be stacked without image degradation or ghosting, in order to provide even narrower passbands.  Or, combine with any of the other Baader filters for interesting possibilities.

No reduction in sharpness, even at high magnifications or when using the filter far ahead of the focal plane (ie, digital imaging, or in front of a diagonal or binoviewer).