A unique filter for many different astronomical tasks. Incomparable in accracy to combinations of generic colour filters made of raw polished glass – where surface inaccuracy adds up in the optical wave front to an unbearable degree!
This high performance CCD filter transmits only the Hydogen Beta emission line, and therefore is useful for greatly increasing the contrast of objects that glow in the corresponding region of the spectrum, for example the Horsehead, Cocoon and California nebulae.
Progressively dims the view when observing the Moon or bright planets whilst increasing contrast, reducing glare and increasing the amount of detail to study.
These contrast-enhancing filters are designed to block out the wavelengths of light emitted by mercury-vapour light and other common causes of light pollution.
