Telescope Comparison
Unistellar Odyssey vs ZWO Seestar S70
The specs are close. The experience isn't.
First light
Unistellar · 50mm · £799
The app-native deep-sky imager
- 50mm sensor-based smart telescope — no traditional eyepiece
- Connects to a smartphone app; the app selects, slews to, and stacks targets automatically
- Best for: faint deep-sky objects — galaxies, nebulae, star clusters built up over minutes
- Not for direct eyepiece viewing — every view is delivered on a phone or tablet screen
- 4.5kg compact all-in-one unit
ZWO · 70mm · £699
The app-native deep-sky imager
- 70mm sensor-based smart telescope — no traditional eyepiece
- Connects to a smartphone app; the app selects, slews to, and stacks targets automatically
- Best for: faint deep-sky objects — galaxies, nebulae, star clusters built up over minutes
- Not for direct eyepiece viewing — every view is delivered on a phone or tablet screen
- 3.2kg compact all-in-one unit
The full picture
The numbers that separate these two scopes — and what they mean at the eyepiece.
Aperture
ZWO Seestar S70 gathers 2× more light. On bright targets — Moon, Saturn, Jupiter — you won't notice. On fainter targets — dim galaxies, faint globular clusters — the gap is real.
Focal length
ZWO Seestar S70's longer focal length reaches higher magnification with the same eyepiece — better reach for planetary detail. Unistellar Odyssey's shorter focal length gives a wider true field — better for large open clusters and extended nebulae.
Focal ratio
Focal ratio is not meaningful for smart telescope sensor systems — the optics are optimised for the built-in sensor rather than interchangeable eyepieces.
Mount type
Same mount type — setup experience and ergonomics will be similar. Differences lie in build quality and included accessories.
Weight (OTA)
ZWO Seestar S70's optical tube is 1.3kg lighter. Relevant if you plan to use it on multiple mounts or carry the tube to dark-sky sites separately.
Optical design
Both sensor-based smart telescopes — no eyepiece, app-controlled, live stacking. The differences are in sensor size, aperture, and companion software quality.
At the eyepiece
| Target | Unistellar Odyssey | ZWO Seestar S70 |
|---|---|---|
| Planets | ||
| Moon | Moderate 50mm aperture limits resolution; craters and maria visible on-screen but fine detail is soft compared to any mid-size visual scope | Good 70mm aperture captures good surface detail, but short 350mm focal length means the disc is small on the sensor and fine detail is limited |
| Saturn | Challenging 200mm focal length produces a very small disc; rings identifiable but no Cassini Division or band detail | Challenging Rings identifiable but very small at 350mm focal length — minimal detail beyond basic ring structure |
| Jupiter | Challenging Disc and Galilean moons visible, but 50mm aperture and short focal length yield minimal cloud band detail | Challenging Disc and Galilean moons visible, but 70mm aperture and 350mm focal length yield a tiny disc with little cloud band detail |
| Mars | Not recommended Tiny disc even at opposition — 50mm aperture and 200mm focal length cannot resolve surface features | Not recommended Sub-70mm effective resolution and very short focal length make Mars a featureless dot even at opposition |
Deep sky | ||
| Orion Nebula (M42) | Good f/4 speed and stacking reveal colour and nebulosity nicely, though 50mm aperture limits faint outer filaments | Excellent Fast f/5 ratio and 350mm focal length frame the full nebula beautifully — stacking reveals extensive nebulosity and colour |
| Andromeda Galaxy (M31) | Excellent 200mm focal length frames the full extent of the galaxy; stacking reveals core, dust lanes, and companion galaxies | Excellent 350mm focal length captures the full extent of the galaxy including outer halo — a signature target for this scope |
| Open clusters | Excellent 200mm focal length gives a wide field ideal for framing large clusters like the Pleiades and Double Cluster | Excellent Wide field at 350mm frames large clusters like the Double Cluster and Pleiades perfectly |
| Globular clusters | Challenging 50mm aperture cannot resolve individual stars; stacking shows a fuzzy glow with brighter core | Challenging 70mm aperture cannot resolve individual stars — globulars appear as soft glowing patches even with stacking |
| Faint galaxies | Challenging Stacking can detect faint targets, but 50mm aperture limits surface detail to soft smudges for most galaxies | Moderate Stacking compensates for the modest 70mm aperture, revealing shapes and structure in brighter galaxies, but faintest targets require long integration times |
| Milky Way / wide field | Excellent 200mm focal length at f/4 is well-suited to sweeping rich star fields and large Milky Way structures | Excellent 350mm at f/5 is ideal for sweeping star fields and Milky Way structures |
Other | ||
| Double stars | Moderate 50mm aperture and screen-based viewing limit resolving power; wide doubles split but close pairs will not separate | Moderate 70mm resolves wider doubles but close pairs are beyond its Dawes limit — and the imaging-only output is not ideal for double star work |
| Astrophotography (deep sky) | Good GoTo tracking and automated stacking produce colour deep-sky images easily, but 50mm aperture and closed ecosystem limit what experienced imagers can achieve | Good Integrated GoTo and tracking with f/5 optics and automated stacking deliver strong deep-sky results; limited by 70mm aperture on faintest targets and lack of manual processing control |
| Astrophotography (planetary) | Challenging 50mm aperture and 200mm focal length produce very small planetary discs with limited detail even with stacking | Challenging 70mm aperture and 350mm focal length produce very small planetary discs with minimal detail |
| Emission nebulae (with dual-band filter) | Not applicable | Excellent Built-in dual-band filter isolates Ha and OIII, making targets like the Veil, Rosette, and Heart nebulae accessible even from light-polluted skies |
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
Unistellar Odyssey
- You'll spend most of your observing time watching the app stack exposures into colour deep-sky images, with the Orion Nebula and Andromeda's core revealing themselves gradually over a few minutes rather than appearing instantly.
- You're trading aperture and focal length for portability and simplicity — a 50mm scope on an integrated tripod is genuinely grab-and-go, but planets like Saturn will be tiny, featureless discs on your screen.
- You're locked into Unistellar's ecosystem; the app handles everything from alignment to stacking, leaving you with no raw files to process elsewhere or settings to tweak, which means a faster learning curve but zero creative control.
ZWO Seestar S70
- You'll spend your first night selecting targets and watching the scope find, focus, and stack them automatically — the experience is even more hands-off than the Odyssey, but you get 40% more aperture and a longer focal length that resolves finer detail in nebulae and galaxies.
- You're trading some portability for real optical capability; the S70 is still all-in-one and lightweight, but its 350mm focal length means fainter objects like the Veil Nebula and Virgo galaxies become viable targets after 15–30 minutes of stacking.
- You can export stacked files from the app for post-processing in external software, giving you more flexibility downstream, though the in-app processing itself offers limited manual control during acquisition.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Unistellar
Unistellar Odyssey
No eyepiece — all observation is screen-based through the Unistellar app; there is no traditional visual astronomy experience.
50mm aperture and 200mm focal length are severely limiting for planets — Saturn is a tiny disc with barely visible rings, and Jupiter shows minimal band detail even on screen.
Integrated lightweight tripod is prone to vibration during long stacking sessions on uneven surfaces or in wind, which can blur the accumulating image.
Closed ecosystem with limited access to raw data or third-party processing tools — you work entirely within Unistellar's app.
ZWO
ZWO Seestar S70
No visual observing — all output is via the app on a phone or tablet; there is no eyepiece option.
70mm aperture and short 350mm focal length are unsuitable for detailed planetary imaging; the Moon shows reasonable surface detail, but Jupiter and Saturn remain small, featureless discs.
In-app processing offers limited manual control — users wanting to adjust exposure or post-process must work with exported stacked files in external software.
Integrated design means individual components (sensor, optics, mount) cannot be upgraded — if any element fails, the entire scope is affected.
Which is right for you?
Two different buyers. Two different right answers.
The app-native deep-sky imager
Unistellar · Unistellar Odyssey
You'll love the Odyssey if you're a beginner in an urban environment who wants instant colour images of nebulae and galaxies without learning astrophotography, or if you're a citizen science participant in Unistellar's SETI Institute programs — the automated stacking and app-first design mean you can have recognisable deep-sky images in minutes with zero setup knowledge. You're not interested in traditional visual stargazing or planetary detail; you just want to see what's out there.
The app-native deep-sky imager
ZWO · ZWO Seestar S70
This is for you if you want a genuinely all-in-one imaging companion that requires no setup knowledge and produces noticeably better results than the Odyssey on deep-sky targets like the Veil Nebula, fainter galaxies, and finely-resolved star clusters — the extra 20mm of aperture and longer focal length translate to real visual gains. You're a complete beginner or an experienced observer who wants grab-and-go imaging without the learning curve, and you don't mind exporting files for post-processing if you want that level of control later.
Our verdict
At similar price points, these scopes offer different amounts of aperture per pound. The ZWO Seestar S70 gives you more light-gathering for your money — and for visual observing, aperture per pound is the most useful single metric.
For pure optical value, the ZWO Seestar S70 is the stronger pick. The Unistellar Odyssey compensates with other features — decide whether those trade-offs justify the premium. If I had to choose: the ZWO Seestar S70 — more aperture per pound means more sky.
Unistellar Odyssey
View Unistellar Odyssey →ZWO Seestar S70
View ZWO Seestar S70 →Deep field: Full specifications
Every data point, for those who want to go further.
Full specifications
Fields highlighted in blue or amber indicate the better value for that spec. Data is manufacturer-stated and may vary.
How much can it see?
| Spec | Unistellar Odyssey | ZWO Seestar S70 |
|---|---|---|
Apertureⓘ The most important spec — bigger = more light = better views | 50mm | 70mm |
Focal Length Longer = more magnification potential | 200mm | 350mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/4 | f/5 |
Optical Design The type of optics — each design has different strengths | Smart Telescope | Smart Telescope |
Coatings Better coatings = more light transmission through the optics | Multi-coated optics | Multi-coated ED doublet objective |
How do you point it?
| Spec | Unistellar Odyssey | ZWO Seestar S70 |
|---|---|---|
Mount Type The mechanical system that holds and moves the telescope | Integrated | Integrated |
GoTo Computer-controlled pointing — finds any of thousands of objects automatically | ||
Tracking Motor keeps objects centred as the Earth rotates — essential for astrophotography |
The focuser
| Spec | Unistellar Odyssey | ZWO Seestar S70 |
|---|---|---|
Focuser Size 2" accepts wider eyepieces and gives better low-power views | — | — |
Focuser Type Rack-and-pinion is standard; Crayford and dual-speed are smoother | Motorised electric focuser with auto-focus | Motorised electric focuser (auto-focus via software) |
Size & weight
| Spec | Unistellar Odyssey | ZWO Seestar S70 |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 4.5kg | 3.2kg |
Total Weightⓘ Full setup including mount — this is what you lug to the car | 4.5kg | 3.2kg |
Tube Material | Aluminium alloy | Aluminium alloy with polycarbonate housing |
What's in the box?
| Spec | Unistellar Odyssey | ZWO Seestar S70 |
|---|---|---|
Diagonal Tilts the eyepiece 90° for comfortable viewing — useful on refractors |
Smart features
| Spec | Unistellar Odyssey | ZWO Seestar S70 |
|---|---|---|
Built-in Camera Records and stacks images automatically — no separate camera needed | ||
App Controlled | ||
WiFi | ||
Battery Included | ||
Sensor | 1/1.8" CMOS | 1/1.8" Sony IMX585 CMOS |
Sensor Resolutionⓘ Higher megapixels captures finer detail | 4MP | 3.8MP |
Blue highlight: Unistellar Odyssey advantage · Amber highlight: ZWO Seestar S70 advantage · Greyed cells: equal or subjective.