Telescope Comparison
Vixen A80Mf vs William Optics Zenithstar 73
The Vixen A80Mf is a complete setup. The William Optics Zenithstar 73 needs a mount before it's usable.
First light
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
William Optics · 73mm · £599
The custom-rig optical tube
- 73mm refractor — optical tube only, no mount included
- 430mm focal length at f/5.89
- 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
The full picture
The numbers that separate these two scopes — and what they mean at the eyepiece.
Aperture
Vixen A80Mf gathers 1.2× 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
Vixen A80Mf's longer focal length reaches higher magnification with the same eyepiece — better reach for planetary detail. William Optics Zenithstar 73's shorter focal length gives a wider true field — better for large open clusters and extended nebulae.
Focal ratio
William Optics Zenithstar 73's faster f/5.89 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
William Optics Zenithstar 73 has no mount — add a compatible mount before you can observe. Vixen A80Mf is a complete ready-to-use system.
Weight (OTA)
Similar optical tube weight. Any portability difference between these setups comes from the mount, not the tube itself.
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 | Vixen A80Mf | William Optics Zenithstar 73 |
|---|---|---|
| Planets | ||
| Moon | 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. | Moderate 73mm aperture shows good crater and terminator detail, but the short 430mm focal length limits useful magnification before the image softens. |
| Saturn | Good 910mm focal length and clean optics show rings clearly separated from the disc; Cassini Division visible in good seeing. | Challenging Rings visible and Titan identifiable, but 73mm aperture and 430mm focal length can't reveal the Cassini Division or subtle banding. |
| Jupiter | Good Two equatorial belts and Galilean moons well defined; the long focal ratio rewards patience in steady seeing. | Moderate Main equatorial belts visible; 73mm falls between the Good and Moderate tiers, and the short focal length makes it hard to push magnification for finer detail. |
| Mars | Challenging Small disc visible at opposition with possible polar cap hint, but 80mm aperture limits surface detail. | Challenging Small disc visible near opposition with possible hint of polar cap, but 73mm aperture and short focal length offer very limited surface detail. |
Deep sky | ||
| Orion Nebula (M42) | Excellent Bright nebula core and trapezium stars well shown at 80mm, though the 910mm focal length crops the nebula's full extent. | Good Core nebulosity and Trapezium visible; the wide field at 430mm frames the full nebula complex nicely, but aperture is just under the 80mm Excellent threshold. |
| Andromeda Galaxy (M31) | Moderate 910mm focal length shows only the bright core region — the galaxy's halo extends well beyond the field of view. | Excellent 430mm focal length frames the full galaxy with room to spare; visually the core and inner dust lanes are visible from dark skies. |
| Open clusters | Moderate Narrow field at 910mm means many clusters overfill the eyepiece; compact clusters like M35 fare better than the Pleiades. | Excellent Wide true field at 430mm is ideal for the Double Cluster, Pleiades, and other large clusters — they sit beautifully in the field of view. |
| Globular clusters | Moderate M13 and M3 appear as granular fuzzy balls — 80mm cannot resolve individual stars in the cluster. | Challenging 73mm aperture shows M13 and M22 as fuzzy unresolved glows — no star resolution possible at this aperture. |
| Faint galaxies | Challenging 80mm aperture limits detection to brighter Messier galaxies as faint smudges; detail is not visible. | Challenging 73mm gathers limited light; only the brightest galaxies like M81/M82 show as faint smudges visually. |
| Milky Way / wide field | Not recommended 910mm focal length produces far too narrow a field for Milky Way sweeping or rich star field context. | Excellent 430mm focal length at f/5.9 delivers sweeping rich star fields — among the best use cases for this scope visually and with a camera. |
Other | ||
| Double stars | Excellent The f/11.4 focal ratio produces clean, tight Airy discs — ideal for splitting doubles down to the ~1.5 arcsecond Dawes limit. | Moderate 73mm resolves wide doubles like Albireo easily, but the short focal length and modest aperture limit splitting of closer pairs. |
| Astrophotography (deep sky) | Not applicable | Not recommended No mount or tracking included; the OTA is excellent for deep sky imaging but only when paired with an equatorial tracking mount purchased separately. |
| Astrophotography (planetary) | Not applicable | Challenging 73mm aperture and 430mm focal length produce a very small planetary image scale — a Barlow helps but aperture is the fundamental limit. |
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
Vixen A80Mf
- You'll spend your observing sessions locked onto the Moon and planets, where the f/11.4 focal ratio rewards you with sharp, high-contrast views that reveal crater detail and Saturn's Cassini Division without the purple fringing of faster scopes.
- You'll become skilled at splitting double stars — the long focal length and smooth Porta II mount make tracking tight pairs at high magnification effortless, turning double-star observing into a reliable pleasure rather than a frustration.
- You'll accept the narrow field of view as a trade-off for optical quality; sweeping the Milky Way or framing the full extent of large nebulae feels cramped, and you'll learn to observe one target at a time rather than exploring.
William Optics Zenithstar 73
- You'll buy an OTA and immediately face the reality that you need a mount, flattener, diagonal, and eyepieces before first light — the £599 price tag is only the beginning of the financial and logistical commitment.
- You'll unlock this scope's potential by pairing it with a camera, where its wide field and fast focal ratio frame entire nebula complexes and galaxy groups in a single exposure, making it a productive wide-field imaging platform even from light-polluted sites.
- You'll find visual observing through it serviceable for bright targets like open clusters and the lunar surface, but underwhelming for planetary detail and deep-sky objects — the scope will constantly remind you it was designed for a sensor, not an eyepiece.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Vixen
Vixen A80Mf
The 910mm focal length creates a narrow true field of view that makes large deep-sky objects like Andromeda's halo and the Orion Nebula's full extent impossible to frame, and Milky Way sweeping is impractical.
80mm aperture fundamentally limits deep-sky visual performance — faint galaxies and globular cluster resolution are beyond reach, leaving you unable to pursue many classic deep-sky observing programs.
Residual chromatic aberration persists on bright stars and the lunar limb, though well controlled for an achromat; the supplied PL eyepieces are basic and upgrading is necessary for the full potential of the optics.
No motorised tracking or GoTo capability restricts astrophotography to brief smartphone snapshots of the Moon and planets, eliminating any serious imaging work.
William Optics
William Optics Zenithstar 73
Sold as OTA only with no mount, eyepiece, diagonal, or finder included — the true cost of a functional setup is significantly higher than the advertised £599 price, and assembly is non-trivial.
The Flat73A field flattener is essentially mandatory for imaging; without it, stars toward the field edges show noticeable coma and curvature, adding another £150+ to the total investment.
As an ED doublet rather than a triplet, residual chromatic aberration is visible on very bright stars in images, though controlled well for the price point.
The 73mm aperture and f/5.9 focal ratio are fundamentally inadequate for visual planetary observing and deep-sky object resolution — this is an imaging instrument first and a visual scope second, if at all.
The 2-inch focuser rack-and-pinion can show minor flexure under heavier camera and filter train loads without careful balancing, requiring attention to mechanical setup.
Which is right for you?
Two different buyers. Two different right answers.
The simple alt-az visual scope
Vixen · Vixen A80Mf
You'll love the A80Mf if you're a beginner seeking a quality refractor that rewards crisp lunar and planetary observing, or if you're a double-star enthusiast who values the long focal ratio and smooth tracking for splitting pairs down to 1.5 arcseconds. This isn't for you if you want to resolve faint galaxies and globular clusters, explore the Milky Way with a wide field of view, or pursue anything beyond snapshot astrophotography.
The custom-rig optical tube
William Optics · William Optics Zenithstar 73
You'll love the Zenithstar 73 if you're committed to wide-field deep-sky astrophotography and willing to invest in a proper equatorial mount, flattener, and camera setup to frame entire nebula complexes and galaxy groups. This isn't for you if you want to observe planets and deep-sky objects visually, prefer a complete ready-to-observe package, or expect to do serious imaging without buying a dedicated flattener and separate mount.
Our verdict
This comparison has a catch: the William Optics Zenithstar 73 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 William Optics Zenithstar 73 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.
Vixen A80Mf
View Vixen A80Mf →William Optics Zenithstar 73
View William Optics Zenithstar 73 →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 | Vixen A80Mf | William Optics Zenithstar 73 |
|---|---|---|
Apertureⓘ The most important spec — bigger = more light = better views | 80mm | 73mm |
Focal Length Longer = more magnification potential | 910mm | 430mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/11.38 | f/5.89 |
Optical Design The type of optics — each design has different strengths | Refractor | Refractor |
Coatings Better coatings = more light transmission through the optics | Multi-coated achromatic doublet | Fully multi-coated FMC ED doublet on all air-to-glass surfaces |
How do you point it?
| Spec | Vixen A80Mf | William Optics Zenithstar 73 |
|---|---|---|
Mount Type The mechanical system that holds and moves the telescope | Alt-Az | None (OTA only) |
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 | Vixen A80Mf | William Optics Zenithstar 73 |
|---|---|---|
Focuser Size 2" accepts wider eyepieces and gives better low-power views | 1.25" | 2" / 1.25" |
Focuser Type Rack-and-pinion is standard; Crayford and dual-speed are smoother | Rack and pinion | Dual-speed Crayford 2" (10:1 reduction fine focus) |
Size & weight
| Spec | Vixen A80Mf | William Optics Zenithstar 73 |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 1.6kg | 1.75kg |
Total Weight Full setup including mount — this is what you lug to the car | 6kg | — |
Tube Length | 910mm | 320mm |
Tube Material | Aluminium | Aluminium, anodised blue |
What's in the box?
| Spec | Vixen A80Mf | William Optics Zenithstar 73 |
|---|---|---|
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: Vixen A80Mf advantage · Amber highlight: William Optics Zenithstar 73 advantage · Greyed cells: equal or subjective.