Telescope Comparison
Sky-Watcher Evostar 100ED vs Vixen A80Mf
The Vixen A80Mf is a complete setup. The Sky-Watcher Evostar 100ED needs a mount before it's usable.
First light
Sky-Watcher · 100mm · £449
The custom-rig optical tube
- 100mm refractor — optical tube only, no mount included
- 900mm focal length at f/9
- Requires a compatible mount before you can observe anything
- Best for: observers who already own a suitable mount or are building a specific imaging rig
- Not a complete purchase — budget at least £100–300 extra for a mount before observing
Vixen · 80mm · £329
The simple alt-az visual scope
- 80mm refractor on a simple alt-az mount
- Good for: Moon, planets, bright open clusters
- No alignment required — quick to set up, intuitive to move
- Finding objects requires learning to star-hop: navigate with a finder scope and sky chart
- 6kg total — manageable to carry to dark-sky sites
The full picture
The numbers that separate these two scopes — and what they mean at the eyepiece.
Aperture
Sky-Watcher Evostar 100ED gathers 1.6× 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
Vixen A80Mf's longer focal length reaches higher magnification with the same eyepiece — better reach for planetary detail. Sky-Watcher Evostar 100ED's shorter focal length gives a wider true field — better for large open clusters and extended nebulae.
Focal ratio
Sky-Watcher Evostar 100ED's faster f/9 delivers wider fields with any eyepiece — better for open clusters and large nebulae. Vixen A80Mf's f/11.38 provides more magnification per eyepiece — better for fine planetary detail.
Mount type
Sky-Watcher Evostar 100ED has no mount — add a compatible mount before you can observe. Vixen A80Mf is a complete ready-to-use system.
Weight (OTA)
Vixen A80Mf's optical tube is 1.0kg lighter. Relevant if you plan to use it on multiple mounts or carry the tube to dark-sky sites separately.
Optical design
Both are refractors — no mirrors to collimate, good contrast, colour-free stars with ED or APO glass. The differences between them are in aperture, focal ratio, and glass quality.
At the eyepiece
| Target | Sky-Watcher Evostar 100ED | Vixen A80Mf |
|---|---|---|
| Planets | ||
| Moon | Excellent 100mm aperture and f/9 focal ratio reward high magnification with sharp, high-contrast lunar detail | Excellent 80mm aperture and f/11.4 focal ratio deliver sharp, high-contrast lunar detail — craters, rilles, and terminator shadows are crisp with minimal chromatic aberration. |
| Saturn | Good 900mm focal length and clean ED optics show rings, Cassini Division in good seeing, and subtle disc banding | Good 910mm focal length and clean optics show rings clearly separated from the disc; Cassini Division visible in good seeing. |
| Jupiter | Good 100mm resolves two or more cloud belts, GRS, and moon shadow transits; f/9 handles high power well | Good Two equatorial belts and Galilean moons well defined; the long focal ratio rewards patience in steady seeing. |
| Mars | Moderate Disc visible with polar cap and large albedo features at opposition, but 100mm limits fine surface detail | Challenging Small disc visible at opposition with possible polar cap hint, but 80mm aperture limits surface detail. |
Deep sky | ||
| Orion Nebula (M42) | Good Bright nebula core and trapezium well shown, but 900mm focal length crops the outer wings | Excellent Bright nebula core and trapezium stars well shown at 80mm, though the 910mm focal length crops the nebula's full extent. |
| Andromeda Galaxy (M31) | Good Bright core and inner halo visible; 900mm frames only the central region, missing the full extent | Moderate 910mm focal length shows only the bright core region — the galaxy's halo extends well beyond the field of view. |
| Open clusters | Good Compact clusters like M35 frame well; larger groups like the Double Cluster fill the low-power field | Moderate Narrow field at 910mm means many clusters overfill the eyepiece; compact clusters like M35 fare better than the Pleiades. |
| Globular clusters | Moderate M13 and M5 appear granular at high power but the core remains unresolved at 100mm | Moderate M13 and M3 appear as granular fuzzy balls — 80mm cannot resolve individual stars in the cluster. |
| Faint galaxies | Moderate Brighter Messier galaxies detectable as smudges; 100mm lacks the aperture for structure or faint targets | Challenging 80mm aperture limits detection to brighter Messier galaxies as faint smudges; detail is not visible. |
| Milky Way / wide field | Not recommended 900mm focal length produces too narrow a field for sweeping Milky Way star fields | Not recommended 910mm focal length produces far too narrow a field for Milky Way sweeping or rich star field context. |
Other | ||
| Double stars | Excellent Clean ED optics at f/9 produce tight diffraction patterns; Dawes limit around 1.2 arcseconds | Excellent The f/11.4 focal ratio produces clean, tight Airy discs — ideal for splitting doubles down to the ~1.5 arcsecond Dawes limit. |
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
Sky-Watcher Evostar 100ED
- You're buying an OTA only — you'll need to source a mount, diagonal, finder, and eyepieces separately, turning a £449 purchase into a £1000+ project before your first observing session.
- You'll spend time dialling in a tracking equatorial mount, but once aligned, planetary detail at 150–200× will reward that effort with razor-sharp crater rims and Cassini Division splits that the smaller scope can't match.
- You'll sacrifice wide-field sweeping entirely — the 900mm focal length crops the Orion Nebula's wings and overfills clusters — but you gain the optical quality to chase tight double stars down to 1.2 arcseconds.
Vixen A80Mf
- You unbox a complete system that works immediately: mount, eyepieces, finder included, so you're observing within an hour rather than weeks of sourcing parts.
- You'll track objects smoothly with manual slow-motion controls on the Porta II mount — no polar alignment, no GoTo setup — making casual lunar and planetary sessions effortless and social.
- You'll reach the Dawes limit at 1.5 arcseconds for double stars and enjoy crisp high-contrast views, but you're observing 20mm less aperture, so Jupiter's detail stays subtle and Mars features remain marginal.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Sky-Watcher
Sky-Watcher Evostar 100ED
Sold as OTA only with no mount, diagonal, finder, or eyepieces included, so actual entry cost is far higher than the £449 price tag suggests.
900mm focal length is too long for wide-field deep-sky imaging without a reducer, and even with reduction it is slower than dedicated f/5–f/7 astrographs.
ED doublet, not triplet — residual chromatic aberration is visible on very bright stars like Sirius, though substantially less pronounced than an achromat.
4.4 kg OTA requires at least a mid-range equatorial mount for imaging stability, adding further cost and complexity.
Vixen
Vixen A80Mf
910mm focal length creates a narrow true field of view, making large deep-sky objects like the full Orion Nebula wings and Milky Way sweeping impractical.
80mm aperture limits deep-sky performance — faint galaxies and globular cluster individual star resolution remain out of reach.
No motorised tracking or GoTo, restricting astrophotography to brief smartphone snapshots of the Moon and planets.
Supplied PL 20mm and PL 6.3mm eyepieces are functional but basic — observers typically upgrade them to improve overall experience.
Residual chromatic aberration is visible on bright stars and the lunar limb, a characteristic limitation of 80mm achromats even at f/11.4.
Which is right for you?
Two different buyers. Two different right answers.
The custom-rig optical tube
Sky-Watcher · Sky-Watcher Evostar 100ED
You'll love this if you're an intermediate observer who already owns a quality equatorial mount and wants the sharpest high-magnification lunar and planetary views possible — the ED optics and f/9 focal ratio deliver genuine Cassini Division splits and crater detail that reward your existing investment. You're not for this scope if you're a beginner expecting a ready-to-observe package, or if wide-field Milky Way sweeping matters to you.
The simple alt-az visual scope
Vixen · Vixen A80Mf
You'll love this if you're a beginner or casual observer who wants a complete, grab-and-observe system that requires zero setup — the Porta II mount and included eyepieces mean you're observing Saturn's rings and the Moon's detail within an hour. You're not for this scope if you need deep-sky resolution or wider fields, or if you're serious about astrophotography beyond lunar snapshots.
Our verdict
This comparison has a catch: the Sky-Watcher Evostar 100ED is a bare optical tube. You cannot use it without a separate mount — which adds meaningful cost and complexity. The Vixen A80Mf is a complete, ready-to-observe package.
For most buyers, the Vixen A80Mf is the right choice — you can observe the same night it arrives. The Sky-Watcher Evostar 100ED makes sense if you already own a compatible mount, or are deliberately building a specific imaging setup piece by piece. If I had to choose for a first telescope: the Vixen A80Mf, without hesitation.
Sky-Watcher Evostar 100ED
View Sky-Watcher Evostar 100ED →Vixen A80Mf
View Vixen A80Mf →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 | Sky-Watcher Evostar 100ED | Vixen A80Mf |
|---|---|---|
Apertureⓘ The most important spec — bigger = more light = better views | 100mm | 80mm |
Focal Length Longer = more magnification potential | 900mm | 910mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/9 | f/11.38 |
Optical Design The type of optics — each design has different strengths | Refractor | Refractor |
Coatings Better coatings = more light transmission through the optics | Fully multi-coated ED doublet | Multi-coated achromatic doublet |
How do you point it?
| Spec | Sky-Watcher Evostar 100ED | Vixen A80Mf |
|---|---|---|
Mount Type The mechanical system that holds and moves the telescope | None (OTA only) | Alt-Az |
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 | Sky-Watcher Evostar 100ED | Vixen A80Mf |
|---|---|---|
Focuser Size 2" accepts wider eyepieces and gives better low-power views | 2" | 1.25" |
Focuser Type Rack-and-pinion is standard; Crayford and dual-speed are smoother | Dual-speed Crayford (with 1.25" adapter) | Rack and pinion |
Size & weight
| Spec | Sky-Watcher Evostar 100ED | Vixen A80Mf |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 2.6kg | 1.6kg |
Total Weight Full setup including mount — this is what you lug to the car | — | 6kg |
Tube Length | 720mm | 910mm |
Tube Material | Aluminium | Aluminium |
What's in the box?
| Spec | Sky-Watcher Evostar 100ED | Vixen A80Mf |
|---|---|---|
Eyepieces Included eyepieces — more is better, but quality matters more than quantity | — | 25mm eyepiece |
Finder Scope Helps you locate areas of the sky before switching to the main eyepiece | — | 6x30 optical finder |
Diagonalⓘ Tilts the eyepiece 90° for comfortable viewing — useful on refractors |
Blue highlight: Sky-Watcher Evostar 100ED advantage · Amber highlight: Vixen A80Mf advantage · Greyed cells: equal or subjective.