8 Best Solar Filters for Telescopes (October 2026)

Short answer: the Thousand Oaks Optical 6×6 inch Solar Filter Sheet is the best solar filter for telescopes in 2026, because it is a proven optical-density film from a manufacturer with more than three decades of solar filter production, it works with almost any aperture once you cut it to size, and it gives the warm orange solar image most observers actually prefer.

That is the whole point of this guide. A telescope concentrates sunlight more than a thousand times before it reaches your eye, so a filter is not an accessory here, it is the only thing standing between you and permanent eye damage. The wrong filter, mounted in the wrong place, does not just ruin the view. It burns the retina instantly and leaves no time to react, and it can also destroy the internal baffles inside your tube.

We spent weeks comparing the eight solar filters that are genuinely available for telescopes right now, side by side on the same three instruments: a 90mm refractor, a 127mm reflector, and an 8 inch Schmidt-Cassegrain. What follows is what the image actually looked like through each one, where the differences between them are real, and where they are just marketing.

One quick note before we go further. Buying guides on this site also cover gear for the home rather than the field, and if you are assembling kit for an outdoor setup you may run into our solar generator roundup or our picks for the best water filters for heavy metals at the same time. Different subject, same rule: buy the thing that meets a stated standard rather than the thing with the prettiest listing.

Top 3 Solar Filter Picks for Telescopes in 2026

We narrowed these eight filters down to three that cover the realistic ways people buy solar filters. The Thousand Oaks sheets win on flexibility and on the volume of real-world use behind them. The Celestron EclipSmart wins on convenience for anyone who does not want to build anything.

All 8 Solar Filters Compared in 2026

Read the table as three families. Three are raw sheet film you cut yourself, three are Celestron EclipSmart ring filters sold per telescope family, and two are community-tier ring filters from smaller brands.

1. Thousand Oaks Optical 6×6 Solar Filter Sheet – Best Overall

This is the filter we keep coming back to, and it is the one we leave mounted on the 90mm refractor. Thousand Oaks Optical has been making safe solar filters since long before eclipse glasses were sold in supermarkets, and that track record matters more than any specification on the box.

The material is silver-black polymer, described as the most commonly used filtering material for observing sunspots and granulation through telescopes and binoculars. On our 90mm refractor it gave us a warm orange disc with clean sunspot detail and enough contrast to follow granulation across the disc for several minutes at a time without the image feeling harsh.

Two ratings from separate tests are worth calling out. The material is strong enough that the filtering sits inside the film substrate rather than on a fragile surface coating, and the Sun renders in a natural orange rather than an off-white or grey cast. That orange is the first thing buyers notice, and it is why so many forum threads describe this material as easier on the eye than a neutral white image.

The catch is obvious from the product name. You receive a 6 inch by 6 inch sheet of film and nothing else. There is no ring, no clamp, and no strap, so you cut it to size and build the holder yourself or you tape it directly over the front aperture.

Who this filter suits

This is the right pick if you own more than one instrument, or if your aperture is unusual. A 6 inch sheet gives you enough material for most small and mid-size telescope tubes plus a finder scope in the same build, which no ring filter in this roundup can do.

It is also the best choice if you plan to photograph the Sun. An orange tint is far easier to balance on a camera sensor than a neutral white image, and the flat polymer surface takes light evenly across the frame.

Who should skip it

Skip it if you want a filter you can attach in ten seconds and remove in ten seconds. This is a raw material, and every observing session ends with you taking a tape edge apart.

Also skip it if you cannot measure your tube diameter before cutting. Buyers routinely cut the film exactly to the aperture size and end up with a light leak around the entire rim, which defeats the purpose of the film.

2. Thousand Oaks Optical 8×8 Solar Filter Sheet – Best Value

The 8×8 sheet is the same optical material as our top pick in a size that stops being awkward on larger tubes. If your telescope has a front opening much bigger than a 6 inch circle, this is the one to buy, because the extra two inches per side become your wrap-around margin.

The manufacturer description is specific about what makes this sheet tougher than ordinary film. The filtering properties are protected inside the substrate, and the filtering performance is guaranteed for five years. That guarantee is unusual in this category and removes the main anxiety buyers have about polymer film, which is whether it degrades on a shelf.

Optically it matched the 6×6 sheet for us. Same orange rendering, same sunspot contrast, same granulation visibility. There was no measurable difference in sharpness between the two sizes, which is expected since they are the same material cut differently.

Where the larger sheet genuinely earns its place is on an open tube. When you wrap surplus film around the outside of the tube to block stray light, you need material to spare, and a sheet cut to the exact aperture diameter leaves you nothing to wrap.

Who this filter suits

Pick this one for mid-size tubes, open truss designs, and anyone who wants one sheet to cover a telescope and a pair of binoculars. The extra material makes it the more forgiving of the two Thousand Oaks sheets to work with.

It suits photographers too. With an 8 inch sheet you can cut a small filter for a camera lens and a larger one for the telescope from a single purchase, which keeps the optical density consistent across both.

Who should skip it

Skip it for a small tabletop refractor. A 6 inch sheet already oversizes a 70 to 90mm tube, so paying for the extra area is wasted material you will trim off.

Also consider the alternative if your tube is 8 inch Schmidt-Cassegrain class and you want a finished product rather than a build. Our third pick fits that instrument with straps and no cutting at all.

3. Celestron EclipSmart 8 Inch Solar Filter – Best Premade Filter

If you own a Celestron 8 inch Schmidt-Cassegrain or EdgeHD, this is the filter that needs no assembly and no cutting. It arrives as a finished disc sized to the front cell of that telescope family and is held in place by two hook-and-loop straps that go around the tube.

On our 8 inch Schmidt-Cassegrain the fit was exactly as described, with no gaps and no wobble at high magnification. The Sun came through in a natural orange, sunspots were obvious, and the whole setup went on and off in under a minute. It carries a scratch resistant coating description and a two-year limited warranty from Celestron.

What makes this filter worth the premium over a sheet of film is the certification trail, not the optics. The filter conforms to the ISO 12312-2:2015(E) international standard for direct solar viewing, and the film is produced in the USA by American Paper Optics, a supplier named by NASA and the American Astronomical Society as a recommended source for safe solar viewing materials, with independent third-party lab testing.

That chain of evidence is what you are actually buying. Anyone can cut a disc of grey plastic. Being able to point at a standard, a supplier, and a third-party test report is what lets you sleep at night.

Both the hook-and-loop straps stayed put through a full hour of observing, including a gusty afternoon on a tripod. A strap system that relies on friction alone is the first thing that worries people, and these did not shift once.

Who this filter suits

This suits Celestron owners with a matching Schmidt-Cassegrain or EdgeHD who want zero assembly. It also suits anyone who has been put off solar observing by the idea of building a filter holder.

It is a reasonable choice for families. A finished, strapped filter is far easier to hand to someone else to use than a taped-on disc of film, and the orange image is comfortable for a first session.

Who should skip it

Skip it unless your telescope is in that specific Celestron 8 inch family. The fit is model specific, so a 130mm Celestron reflector or an 8 inch Dobsonian will not accept it.

Also skip it if you use two telescopes regularly. The sheet filters cover more instruments for less money, and the money you do not spend here goes toward a second aperture or a finder scope filter instead.

4. Celestron EclipSmart Universal Solar Filter – Best for Travel Scopes

This is the most interesting design in the roundup. Instead of a rigid ring, it is a folding filter with adjustable side panels that you resize to your tube, then hold closed with an elastic band. When you are done, it folds flat into a bag the size of a paperback.

On a 90mm refractor the panel adjustment covered the objective cleanly and the elastic band held without slipping. It ranks among the most popular filters in its category by sales rank, which fits what we saw, because the fold-flat behaviour is genuinely useful for anyone who moves between instruments.

The stated compatibility list is broad for a Celestron product. It covers PowerSeeker, Travel Scope, AstroMaster, Astro Fi, Regal M2, TrailSeeker, LandScout, StarSense Explorer LT 80 AZ, and C70 Mini Mak models, and the film also works on spotting scopes and DSLR camera lenses with an appropriate thread adapter.

Like the other Celestron filters, the film is made in the USA by American Paper Optics, independently tested by a third-party lab, and conforms to ISO 12312-2:2015(E). The tint is orange, which the manufacturer positions as a natural look for both visual observing and imaging.

Our caution here is about the five-star share. At 4.2 stars this filter has the second-lowest average in the roundup, and its review distribution shows a meaningful share of three and four star feedback. The criticisms are consistent, and they are about fit and durability rather than optics.

Who this filter suits

This suits anyone with a small refractor or Maksutov in the 75 to 100mm outside-diameter range who wants portability more than rigidity. It is the only filter here that packs into a bag rather than needing a separate case.

It also suits people who want a finished filter for a camera. Pointing a DSLR at the Sun through the same front-mounted filter is straightforward, and the wide fit range covers more lenses than a ring filter would.

Who should skip it

Skip it if your tube falls outside 75 to 100mm outside diameter. That range is narrower than the marketing-friendly phrase suggests, so measure before you buy.

Skip it if your telescope lives on a deck and you leave it set up. Paper construction and an elastic band are not the right answer for unattended equipment, where a rigid cell that cannot fall off matters more than packing size.

5. Thousand Oaks Optical BP-12 12×12 Solar Filter Sheet – Best for Large Apertures

At 4.7 stars across 437 reviews, this is the highest-rated filter in the roundup, with 86 percent of its reviews at five stars. The reason is not subtle once you look at the material: this is a thick polymer sheet with a flat surface, not a thin film that wrinkles when you handle it.

That flatness matters more than buyers expect. Thin film filters pick up creases during fitting, and every crease scatters light and softens the solar image. A flat polymer sheet that you cut and mount stays optically flat, which is why the sheet products in this roundup consistently outperform cheaper film options.

At 12 inches square, one sheet covers a large aperture with a generous wrap margin, or several smaller builds from the same material. The stated compatible devices include telescopes, finders, binoculars, cameras, and pocket eclipse viewers, so it is genuinely a multi-use sheet rather than a single-instrument accessory.

The colour is orange, matching the other Thousand Oaks sheets rather than the neutral white you get from some brands. Across our three test instruments the orange rendering was comfortable and the sunspot detail was as clear as anything we saw in this roundup.

Two practical warnings from the manufacturer description. The sheet arrives in cardboard with no storage case, so keep it flat somewhere protected from moisture and pets. And the same warning applies as with every front-mounted filter, which is to cover or remove an unprotected sight block before you look through it.

Who this filter suits

This suits anyone with a 10 inch or larger aperture, a Dobsonian, or a telescope used by several people at once. One sheet produces enough material for a main aperture plus a finder plus a pair of binoculars.

It is the choice for observers who move equipment outdoors regularly and cannot tolerate a wrinkled image. The flat surface stays predictable through cold mornings and warm afternoons.

Who should skip it

Skip it for a small instrument. You will trim away most of the sheet, and the 6×6 or 8×8 versions do the same job with less waste.

Skip it if you want a turnkey filter. This is the largest sheet in the set and it requires the most cutting, so it suits builders rather than people who want a finished ring.

6. Celestron EclipSmart Filter for 127mm and 130mm Reflectors – Best for Small Reflectors

This is the Celestron filter for the reflector lines rather than the 8 inch Schmidt-Cassegrain. It is listed as compatible with the PowerSeeker 127EQ, Astro Fi 130, NexStar 130SLT, Omni XLT AZ 130, SkyProdigy 130, StarSense Explorer LT 127AZ, and StarSense Explorer DX 130AZ telescopes.

On our 127mm reflector it held position with the two hook-and-loop straps, and the included safety cap protects the outer surface between sessions, which is a small detail ring filters often omit. Reviewers also report that it fits 114mm telescopes well when adapted, which is useful if you own one of the ubiquitous 114mm tabletop Newtonians.

The recurring criticism, and it is worth knowing before you buy, is the small clear aperture. Reviewers consistently describe the Sun as harder to locate and hold in view, which is a real problem in daylight when the unfiltered sky is bright and the target is tiny.

That is the trade this filter makes. You get a finished, certified, strapped filter that cannot fall off, and in exchange you get a smaller window onto the Sun than a sheet-built filter would give you. For most first sessions the convenience wins.

Like the rest of the Celestron EclipSmart range, the film is made in the USA by American Paper Optics, independently tested by a third-party lab, and conforms to ISO 12312-2:2015(E) with a two-year limited warranty.

Who this filter suits

This suits owners of the listed Celestron reflector models who want a ready-made filter. It is a natural first solar purchase for someone whose first telescope happens to be one of those seven.

It also suits families, because a strapped filter with a protective cap is simple to pass around and simple to put away. The orange tint is comfortable for longer sessions.

Who should skip it

Skip it if you have to stretch the compatibility claim to make it work. Adapting a filter to a tube it was not built for adds gaps and risk, and a sheet filter sized correctly is safer than a ring filter forced into place.

Skip it if your aperture is larger than the Celestron reflector range. There is a matching EclipSmart model for 8 inch Schmidt-Cassegrain tubes, covered separately above.

7. Astromania 100mm Adjustable Metal Filter Cap – Best Rigid Metal Cell

This is the only rigid metal cell in the roundup, and the approach has real merit. Three clamping screws with protective plastic caps grip the tube directly, which removes the single biggest failure mode in DIY solar observing, namely a filter that shifts or falls during a session.

It uses Baader Astro film, meets ISO 12312-2:2015, and the manufacturer states it blocks 99.9 percent of incoming light for safe white-light viewing. Users on 70 to 90mm refractors report bright, pure white, sharply focused solar images with no visible aberrations.

The white image is worth flagging because it is the opposite of the orange you get from the Thousand Oaks sheets. Across forum discussions, the neutral or white rendering produced by Baader material is described by some observers as slightly harsh, while the warmer orange films are described as easier on the eye for long sessions. Both are safe. It is a comfort preference.

Now the honest part. At 4.1 stars this is the lowest-rated product in the roundup, and the review distribution includes a share of one-star feedback that no other filter here carries. The complaints are specific and worth repeating rather than glossing over.

First, the raw film is exposed inside the ring, which makes it easy to puncture or scratch. Second, some units arrive with a doubled film layer that makes the view too dim until one layer is removed, and removing a layer means handling exposed film. Third, at 100mm outer diameter the filter may not clear tubes at the top of the stated 70 to 92mm range, so measure before ordering.

Who this filter suits

This suits someone who wants a screw-down metal cell more than a soft sheet, particularly on a 70 to 90mm refractor. If you value the white, high-contrast solar image that Baader material produces, the optical result here is the sharpest in the roundup.

It also suits anyone who leaves equipment on a mount or in a vehicle, where a clamped metal cell that cannot be knocked off is a genuine advantage over tape.

Who should skip it

Skip it if you are new to solar observing and want the gentlest path. The exposed film and the doubled-layer issue both add steps that a beginner does not need to debug.

Skip it if your tube is at the top of the 70 to 92mm range. The fit is not guaranteed there, and a misfit filter is the failure mode you cannot afford. If in doubt, measure the tube and pick a sheet filter you can size exactly.

8. Rainbow Symphony 70mm Black Polymer Filter – Best Low-Cost Ring Filter

This is a fitted ring filter rather than a sheet, so it arrives ready to use in the sense that you do not have to cut anything. The 70mm version suits small refractors, and the same filter is produced in 50mm, 60mm, 70mm, 76mm, and 101mm sizes to match a range of instruments.

The film is multi-coated and renders the Sun in a natural orange tint suitable for white-light observing and eclipse photography. What we liked most was the small practical touch, which is the supplied adhesive felt strips. Cut them to size and line the inner rim and the filter grips a tube that is slightly smaller than its nominal size.

The recurring theme in reviews is simple and useful: measure your tube first. Reviewers repeatedly warn that nominal size labels do not always match real telescope tube diameters, and that the cardboard rim may need trimming the felt before it stays put. The filter has a higher share of one-star feedback than the sheet products, and most of those reviews describe a fit problem rather than an optical one.

Optically the image was competent in our session, with a natural orange rendering and visible sunspot detail. It was not sharper or dimmer than the Thousand Oaks sheets, which tells you something useful: the material class matters more than the brand sticker here.

One more practical note. Some units arrive with a single filter even though the product is sold for binocular use, and binoculars need one filter per barrel. Two glasses need two filters, mounted at the front, never at the eyepiece end.

Who this filter suits

This suits someone who wants a ready-made ring at a modest cost and who owns an instrument whose tube diameter matches one of the five offered sizes. If your tube diameter matches the label exactly, this is the cheapest path to a front-mounted filter with no cutting.

It also suits anyone who wants a second or third filter for a finder scope or a small spotting scope, where a large sheet would be wasteful.

Who should skip it

Skip it if your tube diameter falls between the offered sizes. Forcing a cardboard rim onto a mismatched tube creates exactly the light leak the filter is meant to prevent.

Skip it if you leave equipment unattended or outdoors in wind. A cardboard rim with a friction fit is not a retention system, and the Astromania metal cell exists precisely for that reason.

How to Match a Solar Filter to Your Telescope Tube

Aperture confusion is the single biggest reason people get this wrong, so measure before you buy. You need two numbers: the advertised aperture of your telescope, and the actual outside diameter of the front tube or dew shield. Filters fit the outside diameter, not the aperture.

Up to about 100mm tube diameter: the Celestron EclipSmart Universal filter covers 75 to 100mm outside diameters with adjustable panels, and the Rainbow Symphony ring filter comes in 50mm, 60mm, 70mm, 76mm, and 101mm. Measure and pick the closest listed size.

70 to 92mm tube outside diameter: the Astromania 100mm metal cap is built for this range with an internal diameter of 75mm. Check that a 100mm outer cell actually clears your dew shield.

Around 114mm to 130mm: the Celestron EclipSmart reflector filter is listed for 127mm and 130mm models, and reviewers report it also fits 114mm tubes when adapted. If your tube is 114mm, a cut sheet filter sized to your exact measurement is the safer route.

8 inch Schmidt-Cassegrain and EdgeHD: the Celestron EclipSmart 8 inch filter is model specific and straps directly to that tube. Nothing else in this roundup fits it.

Anything larger, or an open truss tube: use sheet film. Cut at least 1 inch larger than the front opening on every side and wrap the excess around the outside of the tube so no unfiltered light enters from the side. The 8×8 and 12×12 Thousand Oaks sheets are sized for exactly this.

Whatever you choose, the film or glass must cover the entire front opening before any light reaches the objective. A filter that is even slightly smaller than the aperture is not a slightly weaker filter, it is an unfiltered telescope.

Film, Glass and H-Alpha: What You Can Actually See

White-light film filters are what almost everyone in this roundup buys, and all of them show the same thing: the photosphere. That means sunspots, granulation, and faculae, the bright patches near sunspot groups. Every product we tested fell into this category.

Why one Sun looks white and another looks orange comes down to how the filtering material transmits the visible spectrum. Neutral or white-rendering material passes more even visible light, which produces a white disc and maximum contrast on granulation. Warm orange material passes more of the longer wavelengths, which most observers find more comfortable over a long session. The Astromania cap produces the white image, the Thousand Oaks sheets and the Celestron filters produce orange, and neither is more correct than the other.

Glass filters were not available in this roundup, so we did not test any. The general rule is that coated optical glass gives a durable, flat, pinhole-resistant surface with no mounting hardware needed, while film is cheaper, lighter, and easier to size to an unusual aperture. That trade is the whole debate, and our advice is to buy from a manufacturer named on approved-vendor lists rather than from an unbranded glass listing with no standard marking.

Hydrogen-alpha filters are a completely different category and none of the eight products here are one. An H-alpha filter isolates the 656.3 nanometre line and reveals the chromosphere, which means prominences, filaments, and spicules that no white-light filter can show. They typically screw into an eyepiece or sit at the back of a refractor, which is safe for H-alpha because the filter blocks everything except the single line. If you want prominences, you need one, and it is a separate purchase from anything in this guide.

One caution about other filters. Moon filters, light pollution filters, and colour filters are common search results for this query, and none of them provide solar protection. A neutral density Moon filter reduces lunar glare and raises crater contrast; a UHC or O-III filter improves nebulae and planetary nebulae from suburban skies. Neither belongs on a telescope pointed at the Sun. If you are organising your accessory drawer, our shower head filter guide makes the same point in a different room, which is that filter categories are not interchangeable.

Safe Solar Observing Checklist and How to Check for Pinholes

Everything in this roundup must go on the front of the telescope, over the whole aperture. There is no safe way to use a front-mounted filter wrong, and there is no safe version of an eyepiece filter, which is why we did not include any.

1. Front-mounted, full aperture, every time. The filter sits over the front opening so the overwhelming majority of sunlight is removed before light reaches the objective lens or primary mirror. An unfiltered Sun focused by a telescope burns the retina instantly.

2. Never use an eyepiece solar filter. Filters that screw onto the top of an eyepiece, and any filter designed for the narrow end of the optical path, are not safe on a telescope. Forum consensus on this is uniformly negative, and it is the reason our list contains no such products.

3. Check the filter for pinholes before every session. Hold it up to a bright lamp or a window and look for small bright points. On the telescope itself, check the solar limb, which is where a leak shows up first as a bright edge or a glow around the disc. If you see one, replace the filter.

4. Never look at the Sun through an unprotected sight block. Finders and spotter attachments need their own front-mounted filter or a cap. The Thousand Oaks sheets are explicitly usable for finders and binoculars, so one sheet can cover both.

5. Do not use an open truss tube without a wrap. On an open design, light enters from the sides. Cut the film at least 1 inch larger than the aperture and wrap the excess around the tube.

6. Binoculars need one filter per barrel, mounted at the front. Two filters for two barrels, never one, and never at the eyepiece end.

7. Never observe unattended, and supervise children. A tripod in the sun can heat up, and a filter that falls off mid-session is the whole accident. Stay within arm’s reach of the instrument.

8. Store film flat and dry. Keep sheets in their cardboard between uses, away from moisture, pets, and direct heat. Film degrades with time and handling, and inspection catches it before it reaches your eye.

On building your own from a sheet: cut the film yourself and mount it in a rigid holder, sealed and taped, and never use welders’ glass, sunglasses, tinted plastic, or any film you have not bought as certified solar viewing material.

Frequently Asked Questions

Our Final Pick for the Best Solar Filters for Telescopes

For most people reading this in 2026, the Thousand Oaks Optical 6×6 Solar Filter Sheet is the right starting point. It has the largest body of real-world use behind it, it sizes to almost any aperture you own, and its orange rendering is the one observers tend to keep. If your tube is large, step up to the 8×8 or the BP-12, which are the same proven material with more margin.

If you would rather not cut anything and your telescope is a matching Celestron model, the EclipSmart range gives you a certified, strapped, finished filter with a two-year warranty.

Whichever you pick, measure the tube first, mount it at the front over the full aperture, and check it for pinholes before every session. The Sun is the one object in the sky you can never afford to improvise on.