| This Orion Stargazer’s set of four 24mm clear aperture 1.25" eyepiece filters is pre-packaged at a savings over the total cost of the same filters bought individually. Due to the low light transmission of the individual filters, this set is generally most useful with 8" and larger scopes. Each filter comes in an anodized aluminum cell with the name of the filter silk-screened on the rim. The set is packed in a hard plastic storage case and consists of one each of the following 1.25" filters: SkyGlow light pollution
Recommended applications for this filter:
Emission nebulas – Transmits the light of ionized hydrogen and oxygen given off by emission nebulas, while blocking the unwanted glare of city lights and the natural sky glow of ionized gasses in our atmosphere. This improves the visual contrast of the nebulas and make them easier to see from mildly to moderately light-polluted suburban observing sites and dark sky sites alike. Has peak transmission of about 95% at the visually important emission lines of hydrogen-beta at 4861Å and doubly ionized oxygen at 4959Å and 5007Å. Brighter nebulas such as the Dumbbell, Omega, and Lagoon stand out well at suburban sites; faint nebulas such as the Veil, North America, and Pelican are not only visible from suburban sites, but have more detail and higher contrast from dark sky sites. Reflection nebulas – Its wide 650 Ångstrom visual passband makes it useful for enhancing the reflected violet starlight of reflection nebulas from dark sky and suburban sites. However, it is somewhat less useful for this purpose at severely light-polluted sites. Its wide passband allows some blue-white mercury light pollution through, which can reduce the contrast of reflection nebula details. Galaxies – Views of galaxies are somewhat enhanced from light-polluted areas, although not as much as nebulas. Star clusters – Views of star clusters are not enhanced, except those with associated nebulosity, such as the Pleiades. The individual stars of the cluster will be dimmed, but the contrast of the nebulosity will be enhanced.
An individually-measured light transmission curve is supplied with this filter. ND9 neutral gray
Recommended applications for this filter:
Moon – Reduces the brightness and glare caused by irradiation within your eye during lunar observing that can mask small and low contrast details. Reduces eye strain during extended observing by reducing the need to squint. Planets – Reduces the brightness and glare that can mask low contrast details during planetary observing. It does so without affecting the natural colors of the planet being observed, as the light is transmitted through the filter uniformly over the entire visible spectrum, simply reduced in intensity. Bright planetary discs are dimmed to more comfortable observing levels without altering the colors. Binary stars – Helps split binary stars of greatly differing magnitudes by reducing the glare and diffraction around the brighter star of the binary pair.
13% transmission #25A Red
Recommended applications for this filter:
Moon – Somewhat useful for improving contrast between lunar features in scopes 8" and larger. Mercury – Improves observations at twilight, when the planet is near the horizon. Reduces brightness of terrestrial sky to enhance daylight observing. Venus – Reduces brightness of terrestrial sky in daylight observing, allowing occasional terminator deformations to be seen. Mars – Useful for Increasing the contrast and definition of polar caps, frost areas, and maria against the ochre deserts with scopes 8" and larger, particularly when Mars is close to Earth’s horizon, as the red light it passes is the least refracted by air currents in our atmosphere. Jupiter – Very useful in defining blue-tinted cloud formations against lighter-toned atmospheric features. Saturn – Very useful in defining blue-tinted cloud formations and polar regions against the lighter-toned planetary disc. Comets – Enhances the definition of comet dust tails in 10" and larger scopes.
14% transmission #80A Medium Blue
Recommended applications for this filter:
Moon – Very useful as a contrast-enhancing lunar filter under dark sky conditions with scopes 6" and larger. Mercury – May improve observations of rarely visible dusky surface features at twilight, when the planet is near the horizon. Venus – Increases contrast of occasional faint dark shadings in upper Venusian clouds. Mars – Useful for enhancing the visibility of surface features and localized dust storms, clouds, and ice fogs with 8" or larger scopes, particularly during the still-unexplained phenomenon of violet clearing (when the Martian atmosphere – normally a bright, featureless disc in violet light due to the scattering of short wavelengths of light by the thin atmosphere – becomes transparent through a violet or blue filter, revealing large dark surface features). Jupiter – Primarily used for enhancing the boundaries between the reddish belts and adjacent bright zones in the upper atmosphere. Helpful in defining the Great Red Spot and festoons in the belts. Saturn – Brings out details in the belts, zones, and polar regions of the planetary disc. Comets – Brings out the best highlight definition in comet gas tails in 8" and larger scopes.
30% transmission
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