Smart Telescope Guide
| Key Specifications — ZWO Seestar S50 | |
|---|---|
| Aperture | 50mm |
| Optical Design | Triplet apochromatic (APO) refractor |
| Focal Length | 250mm (f/5) |
| Sensor | Sony IMX462 — 2.1MP, 1/2.8" CMOS |
| Built-in Filter | Dual-band: H-alpha (20nm) + OIII (30nm) — switchable |
| Internal Storage | 64GB |
| Mount | Built-in motorised alt-azimuth with tracking |
| Connectivity | Wi-Fi, Bluetooth, USB-C · Seestar app (iOS & Android) |
| Battery | 6,000mAh — ~6 hours per charge |
| Weight | 2.5 kg (including tripod) |
| Included Accessories | Carbon fibre tripod, solar filter, carry case, USB-C cable, dew heater |
| Best For | Nebulae from light-polluted skies, deep-sky imaging, solar observing |
The Seestar S50 is the smart telescope that reviewers consistently recommend first — it's been called the benchmark by BBC Sky at Night, Space.com, and Digital Camera World. It's the right choice if:
The S50 is less ideal if the wide-angle dual-lens capability of the Dwarf 3 appeals to you, or if you want the highest-resolution sensor in the smart telescope class — the S50's Sony IMX462 (2.1MP) is the same resolution as the Dwarf Mini's sensor, not the Dwarf 3's 8.3MP IMX678.
The single most important thing to understand about the Seestar S50 is its built-in dual-band narrowband filter. This is a real optical filter inside the telescope that passes only two narrow bands of light — H-alpha (the red wavelength emitted by hydrogen gas in nebulae) and OIII (the teal-green wavelength from ionised oxygen). Everything else — streetlights, car headlights, the orange glow of an urban sky — is blocked.
The practical effect is dramatic. Targets that a broadband telescope would struggle to pull out of a light-polluted background — the Rosette Nebula, the California Nebula, the Veil Nebula complex — become reachable from back gardens. The Orion Nebula, always a smart telescope showpiece, looks noticeably more structured when imaged through the filter. You get a cooler (bluer-green) colour palette rather than the warmer broadband look, but the contrast and detail in nebula gas is considerably better.
The filter is switchable. The Seestar app automatically engages it for appropriate targets (emission nebulae, primarily), but you can override this for targets like galaxies, star clusters, and the Moon where broadband gives a more natural result. It's a thoughtful implementation — you don't need to understand narrowband imaging theory to benefit from it.
For UK users in particular, this is a significant advantage. Most populated areas in England and Wales sit under Bortle 5–8 skies. The dual-band filter effectively gives you darker-sky results from wherever you are.
The S50's optical specifications — 50mm aperture, 250mm focal length — are shared with both DwarfLab models. What changes with the built-in filter is what's realistically achievable from typical UK locations.
Where the S50 genuinely excels. The Orion Nebula, Rosette, Lagoon, Eagle, Omega, and California Nebulae all respond well to the narrowband filter. The Horsehead Nebula — notoriously difficult from light-polluted sites — is regularly captured by S50 owners in suburban gardens.
Andromeda (M31) is the standout — the S50's field of view frames it well, and the broadband mode shows the core and dust lanes clearly. M81, M82, and the Whirlpool Galaxy (M51) are all achievable from darker sites.
Open clusters are quick, satisfying targets. The Pleiades, Double Cluster in Perseus, Beehive (M44), and Hercules Globular (M13) all image well. Clusters don't benefit much from the narrowband filter, so broadband mode is the right choice here.
The S50 captures detailed lunar images showing craters, rilles, and mountain ranges. The internal 64GB storage saves raw video of the Moon which can be stacked externally with AutoStakkert! for sharper results than the in-app stacking.
With the included solar filter fitted, the S50 images sunspot groups clearly. It's one of very few smart telescopes with solar capability included in the box — and genuinely useful during the current solar maximum period.
Planetary performance is limited by the 50mm aperture — Saturn's rings and Jupiter's main belts are visible, but don't expect fine detail. The S50 is a deep-sky and nebula specialist first; planets are a bonus rather than a core strength.
Rated 4.5/5 by BBC Sky at Night Magazine. Reviewers across BBC Sky at Night, Space.com, Digital Camera World, and AstroBackyard consistently describe it as the benchmark smart telescope — the product everything else is measured against.
The narrowband filter is the most praised feature. Buyers in light-polluted areas (which is most of us in the UK) consistently highlight the filter as a game-changer. Nebula images that should require dark-sky travel turn up from back gardens. This single feature is what drives most S50 recommendations over the DwarfLab models.
ZWO's app and firmware support is responsive. ZWO has a strong track record from their astronomy camera business. Since launch the S50 has received regular firmware updates adding features including mosaic mode (for targets wider than the field of view) and equatorial mode (to reduce field rotation on long sessions).
Battery life is the main limitation flagged. At ~6 hours, the S50's battery is shorter than the Dwarf 3's ~9 hours. Long winter sessions or remote use may require a USB power bank. Connecting one is straightforward and extends runtime indefinitely.
Portrait-orientation sensor can frustrate on wide targets. The sensor sits in portrait (tall) orientation rather than landscape. This is fine for most targets, but wide nebulae like the Andromeda Galaxy or the Pleiades field can feel oddly cropped. Something to be aware of before you try to frame a specific shot.
These are the two most capable smart telescopes currently available in the UK, and the decision between them comes down to one question: do you prioritise the narrowband filter or the higher-resolution sensor and dual-lens system?
The S50's built-in H-alpha + OIII filter makes it the better nebula camera for light-polluted locations — which describes most UK back gardens. It also ships as a complete kit with tripod, case, and solar filter included, making it better value pound-for-pound at the point of purchase.
The Dwarf 3's Sony IMX678 at 8.3MP produces more detail than the S50's 2.1MP sensor on targets where both can reach. Its dual-lens system — simultaneous wide-angle and telephoto capture — is unique in the class and genuinely useful for all-sky timelapses, comet hunts, and sky quality logging. The Dwarf 3 also has a longer battery life (~9 hours vs ~6 hours).
For most UK users in suburban or urban locations, the S50's filter advantage is the deciding factor. For those who specifically want maximum sensor resolution or the wide-angle capability, the Dwarf 3 earns its place.
Read our full Dwarf 3 guide →