Din pacate aceasta descriere nu a fost tradusa momentan in limba romana, din aceasta cauza veti gasi in locul ei descrierea in limba engleza.
This filter works exactly the other way around like a UHC filter: The O-III and H-beta lines are blocked, and all other wavelengths can pass through the filter. It is especially suitable for the observation of weak stars , which lie within a gas-nebula. The gas-nebula is suppressed and the background is black, without the star light is attenuated considerably. The larger the aperture of the telescope, the better the filter works.
Interference filter glass in metal version; no thread.
