Castell #47 Violet / Purple Planetary Filter 5% Transmission - 1.25"
Planetary Colour Filter #47 Violet / Purple 1.25-inch (5% transmission, M28.5x0.6)
Recommended for telescopes with aperture over appr. 150mm.
This filter will improve observations of Venus by improving contrast of dark clouds on Venus' atmosphere. It also highlights the structures in the rings of Saturn. It can even be used for observations of Mercury with telescopes with very large aperture.
Spectrogram of transmission of some colour filters; only for demonstration purposes.