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.
The narrowband UHC filter, like the O-III filter, isolates the two doubly ionized oxygen lines (496 and 501nm) in addition to the hydrogen-beta line (486nm) emitted by planetary and most emission nebulae.
This filter blocks low and high pressure mercury and sodium vapour lamplight and neon light whilst letting the rest of the visible spectrum through. Excellent for viewing all deep sky objects under the urban sky.
Standing for "City Light Suppression", the Explore Scientific 1.25" CLS Nebula Filter is not just for observing nebulous objects, as it lets a broader swathe of wavelengths through to the observer than either the OIII or UHC Explore Scientific filters do.
More versatile than the OIII filter, the Explore Scientific 1.25" UHC Nebula Filter will work on a broader range of nebulous objects, due to its dual peaks in transmissions on both broader OIII lines and Hydrogen wavelengths
This long-pass filter limits transmission of light with wavelengths longer than 650nm. Whilst suppressing all other polluting lights, the filter allows you to observe emission nebulae with greatly enhanced contrast.
A unique filter for many different astronomical tasks. Incomparable in accracy to combinations of generic color filters made of raw polished glass – where surface inaccuracy adds up in the optical wave front to an unbearable degree!