They pass the lines the gas emits and block the rest · review
An oxygen III filter that publishes the two lines it isolates in nanometers — and lists its package weight among its features.
The two doubly-ionized oxygen lines, published in nanometers.
Several of the seven listings on this shelf publish no wavelength at all, and this is one of the three that give a figure rather than a name.
What it means in practice: the filter passes a slice barely wide enough to hold both lines, and blocks the rest of the spectrum. Stars shrink to points, the field goes dark, and a planetary nebula stands out hard against it.
On the Veil or the Ring the effect is not subtle. On a galaxy it removes the object.
The two lines are five nanometers apart, so the window is at least that.
Nothing on the page says how much wider. And that is the trade: a wide oxygen filter lets in more sky glow, a narrow one is less tolerant of a fast telescope.
Four listings on this shelf now publish wavelengths. None publishes a bandwidth, and none publishes a transmission percentage.
The published features include the package weight — one pound — and the package dimensions, three by one by three inches.
The glass weighs a few grams. The figure describes a box.
This site does not print shipping weights as product weights, which is why the table above says no weight is published. The listing says otherwise, in its own features, beside the country of manufacture.
The Veil, the Ring, the Dumbbell, the Crescent, Orion.
All five are places where oxygen III emission dominates, so all five are cases where this filter does what it says. Naming them is a form of specification: it marks the boundary of the product more precisely than any adjective.
What is outside that boundary — galaxies, clusters, reflection nebulae — the page does not mention.
The same maker’s 2 in version, on this same shelf, names an ultra-hard vacuum-deposited coating and claims it eliminates colored halos around bright stars.
This one claims neither.
Same lines, same category, same maker, two diameters — and two different sets of arguments.
American Amazon store sat at about $80 on the day of the survey.
Figures as Keepa reported them on the day this page was last updated. Stock and pricing shift without warning.
Prices quoted in this text were read on October 7, 2026. The live price is at the top of the page.
Same aisle, closest price — what the same spend else shows.
| Bandpass and type | Oxygen III narrowband, isolating just the two doubly-ionized oxygen lines at 496 and 501 nm, per the maker, while blocking the rest of the spectrum · The bandwidth around them is not published · The Veil, the Ring, the Dumbbell, the Crescent and Orion, named by the maker |
|---|---|
| Line transmission | Not published by the maker. |
| Blocking outside the band | The rest of the overall spectrum of light, per the maker · Stated to give extreme contrast between the black sky background and the faint OIII photons · No optical density figure is published |
| Thread size | 1.25 in, written by the maker as 1-1/4 in |
| Glass flatness | Not published by the maker. |
| Coatings | Not published by the maker. · A two-year US warranty and unlimited support are stated |
| Amazon reference | B0007UQNWC |
| EAN | 0050234936231 |
Because it is the package weight, which Amazon listings carry as a shipping figure and which this one has placed among its product features alongside the country of manufacture. The glass itself is a few grams. This site does not publish shipping weights as product weights, which is why the specification table above says the maker does not publish a weight — the figure on the listing describes a box, not a filter. The same applies to the three-by-one-by-three-inch package dimensions published beside it.
A blacker background, and fewer objects. A UHC passes several lines and keeps some of the surrounding continuum, so stars stay visible and nebulae gain contrast. An oxygen filter passes a slice two lines wide, so almost everything except doubly-ionized oxygen disappears — the field goes dark, the stars shrink to points and a planetary nebula stands out hard. On the Veil or the Ring the effect is dramatic. On a galaxy it removes the object. Six filters on this shelf are UHC; two are oxygen.
Not published. The two lines are 496 and 501 nm, so the window must be at least five nanometers wide to take in both, and nothing on the page says how much wider it is. That matters because a wide oxygen filter lets in more sky glow and a narrow one is less tolerant of a fast telescope — the same trade the hydrogen-alpha filter on this shelf leaves unpublished. Across both halves of this shelf, four listings now publish wavelengths and not one publishes a bandwidth or a transmission percentage.
This model is listed on Amazon.com, at ≈ $80 at the last reading. Listed is not the same as in stock: availability changes daily, and the buy box shows the live price.
Details checked on October 7, 2026.
Planetary nebulae and supernova remnants from a suburban garden, on a 1.25 in eyepiece
Specifications: the manufacturer sheet for telescopes and observing optics and the matching Amazon product page. Prices and availability: Keepa. Every figure on this page names its source.
UHC · M28.5 × 0.6 thread · aluminum alloy frame · waterproof coating · no passband published
A UHC filter whose published features include a first-person account of seeing the Orion nebula — and no wavelength anywhere.
Best for: A first nebula filter for a light-polluted sky, bought on price with the specification taken on trust
≈ $23
H-alpha narrowband · 1.25 in · hardened multi-coatings · no bandwidth published
A narrowband hydrogen-alpha filter whose bandwidth — the one figure that defines a narrowband filter — is never published.
Best for: Imaging hydrogen regions, by somebody who will ask the seller for the bandwidth before buying
≈ $70
UHC · 1.25 in standard thread · optical glass in an aluminum frame · anti-reflection coatings · no passband published
A UHC filter that explains correctly what the category does, names the nebulae it suits, and publishes no wavelength at all.
Best for: An observer in a suburban sky who wants the effect explained before buying, and will take the glass on trust
≈ $32
