Telescope Comparison
Askar 103APO vs Vixen ED80Sf
The price gap is real. The question is whether the extra capability is worth it at your stage.
First light
Askar · 103mm · £1,199
The custom-rig optical tube
- 103mm refractor — optical tube only, no mount included
- 700mm focal length at f/6.8
- 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 · £649
The custom-rig optical tube
- 80mm refractor — optical tube only, no mount included
- 600mm focal length at f/7.5
- 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
Askar 103APO gathers 1.7× 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
Askar 103APO's longer focal length reaches higher magnification with the same eyepiece — better reach for planetary detail. Vixen ED80Sf's shorter focal length gives a wider true field — better for large open clusters and extended nebulae.
Focal ratio
Askar 103APO's faster f/6.8 delivers wider fields with any eyepiece — better for open clusters and large nebulae. Vixen ED80Sf's f/7.5 provides more magnification per eyepiece — better for fine planetary detail.
Mount type
Neither scope includes a mount — both require a separate purchase before you can observe.
Weight (OTA)
Vixen ED80Sf's optical tube is 2.0kg 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 | Askar 103APO | Vixen ED80Sf |
|---|---|---|
| Planets | ||
| Moon | Excellent 103mm aperture delivers sharp crater detail and clean terminator views; the ED triplet produces essentially no chromatic fringing on the bright limb | Excellent 80mm aperture with ED glass delivers sharp, colour-free crater detail; f/7.5 handles high magnification well |
| Saturn | Good Rings clearly defined, Cassini Division visible in steady seeing; 700mm focal length supports useful magnification but aperture limits fine banding detail | Good Rings clearly defined, Cassini Division visible in steady seeing; 600mm focal length adequate for useful magnification with a short Barlow |
| Jupiter | Good Two main equatorial belts and GRS visible; 103mm resolves some secondary belts in good seeing but can't match larger apertures for fine atmospheric detail | Good Main equatorial belts and GRS visible; ED glass keeps the limb clean, but 80mm limits fine belt detail |
| Mars | Moderate Small disc visible with polar cap detectable near opposition; 103mm and 700mm focal length limit the detail available on this demanding target | Challenging Small orange disc visible at opposition; polar cap hints possible but aperture too small for surface detail |
Deep sky | ||
| Orion Nebula (M42) | Excellent 103mm gathers plenty of light and 700mm focal length frames the full nebula complex well; Trapezium resolved and nebulosity extends visually | Excellent 80mm aperture and 600mm focal length frame the full nebula with surrounding structure; trapezium resolved |
| Andromeda Galaxy (M31) | Excellent 700mm focal length keeps the full extent of M31 in the field; 103mm aperture shows the bright core and hints of dust lanes | Excellent 600mm focal length captures the full extent of the galaxy; bright core and inner dust lanes visible |
| Open clusters | Excellent 700mm focal length and wide true field frame showpiece clusters like the Double Cluster and Pleiades beautifully | Excellent 600mm focal length gives wide true field — Pleiades, Double Cluster, and M35 all fit beautifully with pinpoint stars |
| Globular clusters | Moderate 103mm shows a granular, textured ball but cannot resolve individual stars in the core; M13 and M3 appear mottled at best | Moderate M13 and M3 appear as fuzzy concentrated balls; 80mm cannot resolve individual stars |
| Faint galaxies | Moderate 103mm aperture detects brighter Messier galaxies as smudges but struggles with fainter NGC targets visually | Moderate Brighter Messier galaxies (M81/M82, M51) visible as faint smudges; no structure detail at 80mm |
| Milky Way / wide field | Good 700mm is slightly long for sweeping starfield views but still delivers rich fields; a reducer brings it closer to wide-field territory | Good 600mm is slightly long for sweeping Milky Way fields but still delivers rich star clouds with a wide-field eyepiece |
Other | ||
| Double stars | Good 103mm resolves doubles to about 1.1 arcsecond; f/6.8 is not ideal for high-magnification splitting but the clean optics help | Good Clean ED optics split Albireo easily and handle tighter pairs like Castor; Dawes limit ~1.45 arcsec |
| Astrophotography (deep sky) | Not recommended No mount or tracking included; with a suitable equatorial mount this scope would rate Excellent — f/6.8, 103mm aperture, and ED triplet design are ideal for deep-sky imaging | Not applicable |
| Astrophotography (planetary) | Moderate 103mm aperture captures reasonable planetary detail with a high-speed camera, but aperture and focal length limit resolution compared to larger scopes | Not applicable |
| Emission nebulae (imaging) | Excellent 700mm at f/6.8 frames large emission nebulae like the Heart, Soul, and North America Nebula well on APS-C sensors; tight star correction across the field with a matched flattener | Not applicable |
| Galaxy groups (imaging) | Good 700mm focal length provides enough scale for galaxy groups like the Leo Triplet or M81/M82 on common sensor sizes while keeping good signal-to-noise at f/6.8 | Not applicable |
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
Askar 103APO
- You're building an imaging rig, and you know it — you'll pair this with an HEQ5 or EQ6, a dedicated cooled camera, and a field flattener, and your total outlay will sail past £3000 before you capture a single sub.
- You'll be rewarded with tight, colour-free stars across your sensor at 700mm, which is the sweet spot for framing galaxies like the Leo Triplet with enough resolution to pull out spiral arm detail in processing — something the 80mm simply can't match.
- You'll feel the extra weight on setup night: roughly 5–6kg of OTA plus camera and guide scope means you need a mount that can handle the load, and you'll spend longer balancing and settling before your autoguider locks on.
Vixen ED80Sf
- You'll grab this tube for a quick visual session and genuinely enjoy it — the colour-clean lunar views and wide-field sweeps of open clusters feel effortless, and the compact size means you actually take it out on weeknights.
- You can image with it too, but you'll notice f/7.5 demands longer exposures than the Askar's f/6.8, and the 1.25"-only focuser on the standard model limits your accessory options when you start upgrading your imaging train.
- You'll spend roughly half what the 103APO costs on the OTA alone, which leaves real budget for a mount — but you'll always know that 80mm of aperture is gathering 40% less light than 103mm, and on faint nebulae that gap shows up starkly in your stacked data.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Askar
Askar 103APO
At £1199 for the OTA alone — no mount, no diagonal, no eyepieces — your total imaging system cost will comfortably exceed £3000, making this a serious financial commitment before you see first light.
The f/6.8 focal ratio is moderate, not fast: compared to dedicated f/5 or faster astrographs, you'll need noticeably longer exposures to pull faint emission detail, eating into your imaging time on short nights.
You'll need a matched field flattener or reducer for proper edge-of-field star shapes on APS-C or larger sensors — without one, edge stars will show elongation that no amount of post-processing can fully fix.
Vixen
Vixen ED80Sf
The standard model's 1.25"-only focuser is a real limitation: you can't use 2" wide-field eyepieces or larger imaging accessories without upgrading, which narrows your growth path.
At £649 for 80mm of aperture, you're paying a premium for ED glass and Vixen build quality rather than light-gathering power — a 130mm Newtonian at this price would show you far more on faint deep-sky targets.
Without a dedicated field flattener, coma and field curvature at the edges of camera sensors will produce stretched stars — an added cost and complexity you'll discover as soon as you start imaging.
Which is right for you?
Two different buyers. Two different right answers.
The custom-rig optical tube
Askar · Askar 103APO
You've already been imaging with an 80mm refractor and you're ready to step up — you want tighter stars, more focal length for galaxy season, and a triplet ED design that won't leave colour halos in your data. You understand that this OTA is one piece of an expensive system, you already own (or plan to buy) an HEQ5-class mount, and you're willing to invest in the flattener, guide scope, and camera to build a serious deep-sky imaging platform. This isn't for you if you want something you can observe through on a casual night — at this price, a 10" Dobsonian would crush it visually.
The custom-rig optical tube
Vixen · Vixen ED80Sf
You want one tube that does a bit of everything without punishing you for it — you'll sweep the Milky Way visually on clear evenings, shoot widefield nebulae when the mood strikes, and appreciate the Vixen's compact form factor when you're hauling gear to a dark site. You value build quality and chromatic correction over raw aperture, and you're comfortable knowing 80mm will never wow you on galaxies or globular clusters. This isn't for you if you're a dedicated astrophotographer chasing faint targets — the smaller aperture, slower focal ratio, and 1.25" focuser will feel limiting sooner than you expect.
Our verdict
At £649 versus £1,199, the Askar 103APO costs 85% more. It delivers 23mm more aperture — a real and visible advantage on faint targets.
If budget is a genuine constraint, the Vixen ED80Sf will make you a happy observer. The Askar 103APO's optical advantage on faint targets is real and you are unlikely to regret it if you can stretch. If I had to choose without knowing your situation: start with the Vixen ED80Sf, use it for a year, then upgrade knowing exactly what you want.
Askar 103APO
View Askar 103APO →Vixen ED80Sf
View Vixen ED80Sf →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 | Askar 103APO | Vixen ED80Sf |
|---|---|---|
Apertureⓘ The most important spec — bigger = more light = better views | 103mm | 80mm |
Focal Length Longer = more magnification potential | 700mm | 600mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/6.8 | f/7.5 |
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 triplet on all air-to-glass surfaces | Fully multi-coated ED doublet on all air-to-glass surfaces |
How do you point it?
| Spec | Askar 103APO | Vixen ED80Sf |
|---|---|---|
Mount Type The mechanical system that holds and moves the telescope | None (OTA only) | 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 | Askar 103APO | Vixen ED80Sf |
|---|---|---|
Focuser Size 2" accepts wider eyepieces and gives better low-power views | 2" / 1.25" | 2" |
Focuser Type Rack-and-pinion is standard; Crayford and dual-speed are smoother | Dual-speed Crayford 2" (10:1 reduction) | Dual-speed Crayford (with 1.25" adapter) |
Size & weight
| Spec | Askar 103APO | Vixen ED80Sf |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 3.8kg | 1.8kg |
Tube Length | 550mm | 528mm |
Tube Material | Aluminium | Aluminium |
What's in the box?
| Spec | Askar 103APO | Vixen ED80Sf |
|---|---|---|
Diagonal Tilts the eyepiece 90° for comfortable viewing — useful on refractors |
Blue highlight: Askar 103APO advantage · Amber highlight: Vixen ED80Sf advantage · Greyed cells: equal or subjective.