The Best Filters for Smart Telescopes: Built-In, Dual-Band, Broadband and Solar

Filters are where smart telescope brands differ most, and where buyers waste the most money. Some scopes come with everything you need built in. Others leave you to buy the one filter that matters most for city nebulae. And plenty of add-on filters on Amazon either don’t fit your scope or don’t help the targets you care about.

This guide sorts it out: what each brand includes, what the main filter types do, and which add-ons actually fit which telescope. It’s research-based (we haven’t tested these filters ourselves), using maker spec pages, retailer pages and the accessory listings we checked on Amazon on November 12, 2026. Prices change, so check today’s price before you buy.

The four filter types, briefly

UV/IR-cut (clear). The default on every smart scope that has a filter wheel. It keeps stars sharp and colors natural. Use it for galaxies, clusters and the Moon.

Dual-band or narrowband (H-alpha + OIII). Emission nebulae glow mostly in two narrow colors: deep red hydrogen-alpha and teal oxygen-III. A dual-band filter passes those and blocks most other light, including much of the glow from LED streetlights. Narrower passbands block more skyglow: First Light Optics describes the Optolong L-eXtreme’s two 7 nm passbands with nothing transmitted between H-beta and OIII. The built-in filters on Seestar and Dwarf scopes are wider (15–30 nm).

Broadband light-pollution (CLS, L-Pro). These cut the specific spectral lines of old sodium and mercury-vapor streetlights while keeping most starlight. They help modestly under that kind of lighting and much less under modern white LEDs, which spread their light across the spectrum.

White-light solar. A dense filter that blocks almost all sunlight before it enters the telescope. It must be a proper full-aperture filter fitted securely over the front. It’s the only filter type here that’s safe for the Sun. FLO notes even the L-eXtreme isn’t for solar use.

What a dual-band filter is worth

Our integration-time estimator shows the difference. For the Rosette Nebula on a Seestar S50 Pro from a Bortle 8 city sky, it estimates about 2.2 hours with the built-in dual-band filter and about 8 hours without. For the Pinwheel Galaxy, a broadband target, the filter changes nothing, and the tool doesn’t apply it. For more on picking targets by sky, see smart telescopes in the city.

What each brand includes

ZWO Seestar: nothing essential to buy

Every current Seestar has a duo-band filter built in alongside the UV/IR-cut and dark filters, so emission nebulae get the benefit without an extra purchase. All three ship with a solar filter. That’s why the Seestar S50 Pro is our default recommendation: at about $999 you get the full filter kit without extras. Check the S50 Pro price.

The one upgrade S50 Pro owners ask about is a tighter narrowband filter for very bright cities. The West Coast Astro 2-inch filter adapter (about $13) is a 3D-printed part that holds a standard 2-inch filter in front of the built-in filter wheel. The seller says it does not fit the S30, S30 Pro or original S50, so it’s an S50 Pro-only accessory.

DWARFLAB: built-in, with an optional 2-inch route

The Dwarf 3 has a dual narrowband filter with a 15 nm H-alpha passband, slightly tighter than the Seestars’ 20 nm, plus a magnetic solar filter in the box. At about $549 it’s the cheapest way into a 4K sensor with that setup. Check the Dwarf 3 price.

If you want to add a 2-inch filter, the ZTMXHYKH M48 adapter for the Dwarf 3 (about $32) holds one and doubles as a dew shield. It’s a third-party part from a marketplace seller with no reviews yet when we checked, so treat it as a gamble. The Dwarf Mini also has built-in filters and an included solar ND filter.

Vaonis Vespera: budget for filters

No Vespera has built-in filters, so the Vespera II, 3 and Pro 2 all image through clear glass unless you add one. Vaonis’ comparison page lists light-pollution, dual-band and solar filters as separate purchases, and Zelpio’s Vespera 3 review puts the dual-band filter at about $400 (12 nm) and the solar filter at about $150.

• Vaonis Vespera Dual Band filter (about $379): H-alpha + OIII, detected automatically by the Vespera. Caveat: the listing is sold for “Vespera”, and Vaonis’ newer Vespera 3 and Pro 2 listings don’t confirm this exact part. Check Vaonis’ compatibility list before ordering.
• Vaonis Light Pollution (CLS) filter (about $217): a broadband filter on the Vespera’s 78 mm thread. Fine under sodium lighting, weak under LEDs.

If you’ll image nebulae from a suburb, add roughly $400 to the Vespera 3’s price when comparing it with a Seestar.

Celestron Origin: the filter drawer

The Origin Mark II has a filter drawer that takes 1.25-inch and 2-inch filters. Celestron’s own Nebula Narrowband filter for Origin (about $219) is a tri-band (H-alpha, H-beta, OIII) filter listed as exclusively for the Origin. It’s the single biggest upgrade for emission nebulae from suburban skies, and it does nothing for galaxies or star clusters. There’s no solar option for the Origin at all: never point it at the Sun.

Unistellar: software instead of glass

Unistellar’s Odyssey, Odyssey Pro, eQuinox 2 and eVscope 2 have no physical light-pollution filter. They rely on software reduction that Unistellar calls Deep Dark Technology. A Smart Solar Filter is sold separately.

Third-party 2-inch filters: which fits what

Only scopes with a 2-inch adapter can take these. On our list that means the S50 Pro (with the West Coast Astro adapter) and the Dwarf 3 (with an M48 adapter).

• Optolong L-eXtreme 7 nm (about $259): the go-to filter for nebulae from heavily light-polluted skies. Only useful on emission nebulae. Retailers such as High Point Scientific stock the same 2-inch version.
• Optolong L-eNhance (about $216): a wider tri-band (H-alpha, H-beta, OIII) filter. Brighter stars and shorter exposures than the L-eXtreme, a little less contrast in bright cities.
• Optolong L-Pro (about $198): broadband, for galaxies and clusters under moderate suburban skies where narrowband doesn’t help.

Be realistic about gains. Going from a built-in 20–30 nm dual-band filter to a 7 nm one improves contrast in very bright skies, but it’s a refinement, not the jump you get from no filter to any dual-band filter.

Which filter should you buy?

• You own a Seestar or Dwarf: probably nothing. Use the built-in dual-band filter for nebulae and the clear filter for everything else.
• S50 Pro owner in a Bortle 8–9 city who images lots of nebulae: the West Coast Astro adapter plus an L-eXtreme.
• Vespera owner in the suburbs: Vaonis’ dual-band filter, after confirming compatibility with your model.
• Origin owner: Celestron’s Nebula filter for emission nebulae; leave it out for galaxies.
• Anyone imaging the Sun: only the maker’s solar filter, fitted over the front. See our solar guide.

How we chose

We started from the filter specs in the maker pages for all 15 telescopes we track, then matched every add-on to the scopes its Amazon listing or seller confirms. Where fit isn’t confirmed (the Vaonis Dual Band on the Vespera 3, the Dwarf 3 M48 adapter), we say so rather than guess. Time estimates come from our integration-time estimator, which is a planning model, not a measurement. More on our process on how we research, and for a brand-level view, see Seestar vs Vespera vs Unistellar and our best smart telescopes of 2026.