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Orion UltraBlock Narrowband Filter - 1.25" Round Mounted

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Orion UltraBlock Narrowband Filter - 1.25" Round Mounted

Orion 1.25" UltraBlock Telescope Filter

If you observe from highly light-polluted sites, or if you want the maximum contrast enhancement in observing faint emission nebulas from areas of moderate light pollution, an Orion UltraBlock filter is for you. With an UltraBlock, emission and planetary nebula are even visible from urban areas, where they are completely invisible without a filter! In darker-sky locations with only moderate light pollution, many objects will appear significantly enhanced over unfiltered and wideband filtered views.

Orion UltraBlock Telescope Filters block all forms of light pollution, including both narrowband mercury- and sodium-vapor lighting and broadband light pollution sources. UltraBlock Filters reject pollution from incandescent and fluorescent lighting, which wideband filters can't stop. Extremely high (99.9%) blocking of critical mercury and sodium emission bands and very high transmission of hydrogen-beta and ionized oxygen wavelengths result in the highest contrast gain of any competing light pollution filter.

Orion 1.25" UltraBlock Telescope Filter Features

  • In areas plagued with significant light pollution, our UltraBlock eyepiece filter greatly increases contrast of emission and planetary nebulas
  • Allows you to see features and details through a telescope that would normally be lost due to light pollution
  • Blocks all forms of light pollution while passing critical hydrogen-beta and ionized oxygen wavelengths of light
  • Enhances the sky presence of a significant number of fainter deep-sky objects
  • Use with any 1.25" Orion eyepiece threaded for filters
Orion Product Number: 5654

A User's Report: "The Orion UltraBlock filter was a real surprise for this observer. It of course reduces the brightness of stars, and diminishes the image of globular clusters, but the resultant black sky background is astonishing. On my first try of the UltraBlock, I observed the Orion Nebula rising just above my roof early one evening. The entire sky was pink to the naked eye, and hardly any background stars were visible in the telescope. The nebula was a washed-out and vague caricature of the stunning sight that it is in a desert sky. In went the UltraBlock, and suddenly the faint tendrils of glowing clouds were visible, against a velvety deep-black background! I eagerly turned the telescope to the Pleiades, and the UltraBlock unmistakably brought out the nebulosity around several of the brightest a 4" telescope! In a few moments I had found the vague cloud of M1, which I have never been able to view from my urban front yard. Before using the UltraBlock, I had felt that my front yard was suitable only for planetary observing. Now that I'm hooked on the UltraBlock, I spot a new Messier object within minutes each time I take out my telescope."



Accessory TypeContrast Booster & Light Pollution Reduction
Filter MountedMounted
Filter Side Adapter SizeRound
WarrantyOrion Limited Warranty

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Functional filter for emission nebulae ONLY

Due to a freak of nature, the OIII and H-beta emission lines at around 500nm roughly correspond to the most sensitive wavelength of scotopic (night-adapted vision. This filter will pass those lines while blocking most other light, affording a significant increase on visibility for a wide variety of emission nebulae. It will NOT appreciably improve the view of galaxies or star clusters. A nice filter to have in your arsenal.