Telescope Comparison
Askar 80PHQ vs William Optics GT102
The specs are close. The experience isn't.
First light
Askar · 80mm · £799
The custom-rig optical tube
- 80mm refractor — optical tube only, no mount included
- 448mm focal length at f/5.6
- 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
William Optics · 102mm · £999
The custom-rig optical tube
- 102mm refractor — optical tube only, no mount included
- 714mm focal length at f/7
- 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
William Optics GT102 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
William Optics GT102's longer focal length reaches higher magnification with the same eyepiece — better reach for planetary detail. Askar 80PHQ's shorter focal length gives a wider true field — better for large open clusters and extended nebulae.
Focal ratio
Askar 80PHQ's faster f/5.6 delivers wider fields with any eyepiece — better for open clusters and large nebulae. William Optics GT102's f/7 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)
Askar 80PHQ's optical tube is 1.2kg 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 80PHQ | William Optics GT102 |
|---|---|---|
| Planets | ||
| Moon | Excellent 80mm aperture delivers sharp lunar detail; short focal length limits magnification but crater fields and terminator are crisp | Excellent 102mm APO delivers razor-sharp, colour-free lunar detail; f/7 rewards medium-high magnifications cleanly |
| Saturn | Good Rings clearly visible at modest magnification; 448mm focal length limits high-power planetary detail | Good Rings well-defined, Cassini Division visible in steady seeing; 714mm focal length limits image scale for fine detail |
| Jupiter | Good Main cloud belts and Galilean moons visible, but the short focal length constrains useful magnification | Good Two main cloud belts and GRS visible with no chromatic aberration; a Barlow extends reach for more detail |
| Mars | Challenging Small disc visible at opposition; 80mm aperture and 448mm focal length insufficient to resolve surface features reliably | Moderate Disc visible with polar cap at opposition; 102mm aperture limits surface albedo detail |
Deep sky | ||
| Orion Nebula (M42) | Excellent Bright target framed beautifully by the wide field; f/5.6 speed and sub-600mm focal length show full nebula extent | Excellent 102mm gathers ample light; 714mm frames the full nebula extent with surrounding context |
| Andromeda Galaxy (M31) | Excellent 448mm focal length captures the full extent of M31 including outer halo; 80mm aperture adequate for the bright core and dust lanes | Excellent 714mm focal length captures the bright core and extended halo; 102mm aperture aids outer arm visibility |
| Open clusters | Excellent Wide field at 448mm frames large clusters like the Double Cluster, Pleiades, and Hyades superbly | Excellent Wide field at 714mm frames clusters like the Double Cluster beautifully with pinpoint stars |
| Globular clusters | Moderate 80mm aperture shows bright globulars like M13 as granular but unresolved fuzzy patches | Moderate M13 appears granular with a bright unresolved core; 102mm cannot resolve individual stars throughout |
| Faint galaxies | Moderate 80mm aperture detects brighter Messier galaxies as smudges; insufficient light grasp for dim NGC targets visually | Moderate 102mm aperture shows brighter Messier galaxies as fuzzy patches; fainter NGC targets need more aperture visually |
| Milky Way / wide field | Excellent 448mm focal length at f/5.6 — ideal for sweeping rich star fields and Milky Way structure | Good 714mm is at the upper end for star-field sweeping; rich fields are enjoyable but the true field is narrower than sub-500mm scopes |
Other | ||
| Double stars | Good 80mm resolves wider doubles cleanly; the fast f/5.6 focal ratio is less ideal than a long-FL refractor for tight pairs | Excellent 102mm resolves to ~1.1 arcsec; clean APO optics give textbook Airy discs and tight diffraction-limited splits |
| Astrophotography (deep sky) | Not recommended OTA only with no mount — requires a separate equatorial or GoTo mount for any deep-sky imaging; on a suitable mount this would rate Excellent | Not recommended No mount or tracking included — requires separate equatorial mount purchase; on a suitable mount this OTA would rate Excellent at f/7 with triplet correction |
| Astrophotography (planetary) | Challenging 80mm aperture and 448mm focal length undersized for planetary imaging; a Barlow helps but cannot overcome the aperture limit | Moderate 102mm aperture limits planetary detail capture; focal length benefits from a 2–3× Barlow for adequate image scale |
| Wide-field emission nebulae (imaging) | Excellent Fast f/5.6 quad APO with integrated flattener is purpose-built for targets like the Veil, North America, and Rosette Nebulae on a suitable mount | Not applicable |
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
Askar 80PHQ
- You'll point this at a huge emission nebula like the North America or Rosette, fire off 60-second subs at f/5.6 without an external field flattener, and wake up to a stack with pinpoint stars corner to corner on a full-frame sensor — that integrated quadruplet design means fewer accessories, fewer spacing headaches, and faster accumulation of photons on faint targets.
- You'll travel light — the 80PHQ is compact and featherweight enough to ride a mid-range EQ mount like an iOptron GEM28 or even a Star Adventurer GTi, so you're more likely to actually pack it in the car for a dark-sky trip instead of leaving it at home.
- You'll rarely, if ever, put an eyepiece in this focuser — and if you do, 80mm of aperture at 448mm focal length gives you pleasant wide-field sweeps of bright clusters but nothing rewarding on planets or faint galaxies, so this scope only earns its keep when a camera is attached.
William Optics GT102
- You'll set this up on an HEQ5 and frame individual galaxies like M51 or the M81/M82 pair at 714mm, pulling real structural detail and clean colour data across your APS-C or full-frame sensor — the extra aperture and focal length reward patience with finer resolution on smaller targets the 80PHQ simply can't reach.
- You'll actually enjoy visual nights with this scope — the 102mm triplet APO delivers genuinely sharp, colour-free views of Saturn's rings, Jupiter's belts, and lunar craters, so on evenings when you don't feel like setting up the imaging train, you still have a capable grab-and-go refractor.
- You'll pay for that versatility with slower imaging speed — at f/7, emission nebulae demand noticeably longer total integration times than the 80PHQ's f/5.6, and you'll need to buy a matched field flattener separately to cover a full-frame sensor cleanly, adding cost and back-focus fiddling.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Askar
Askar 80PHQ
The 80PHQ is an OTA only — no mount, finder, diagonal, or eyepiece is included, so budget at least as much again for even a basic equatorial imaging setup before you capture a single frame.
Back-focus spacing must be exactly ~55mm to deliver the flat field the quadruplet promises; get it wrong by a millimetre or two and you'll see field curvature and elongated corner stars that undermine the whole point of the design.
Some users report the stock focuser flexes under heavier camera payloads — if you're running a full-frame cooled camera with a filter wheel, you may end up investing in an aftermarket focuser upgrade.
William Optics
William Optics GT102
Also OTA only — no mount, diagonal, finder, or eyepieces included, and the GT102 needs at least an HEQ5-class mount for stable guided imaging, pushing total system cost well beyond the £999 OTA price.
Full-frame imaging without the separately purchased matched field flattener produces noticeable edge star distortion, so budget for that accessory from day one if you're shooting on a large sensor.
Some production runs lack a built-in focuser lock, and imagers using heavier camera setups may find themselves chasing focuser slip or investing in a motor focuser to maintain critical focus through long sessions.
Which is right for you?
Two different buyers. Two different right answers.
The custom-rig optical tube
Askar · Askar 80PHQ
You'll love the 80PHQ if you're a dedicated deep-sky imager who wants the widest, fastest field you can get in a compact refractor — you already own an equatorial mount, you know what back-focus spacing means, and your target list is dominated by large nebulae and sweeping Milky Way star fields that benefit from f/5.6 speed and a 4.6° full-frame field. This isn't for you if you want any meaningful visual capability, if you're new to astrophotography and need a complete starter package, or if your targets are small galaxies and planetary nebulae that demand more focal length and aperture.
The custom-rig optical tube
William Optics · William Optics GT102
You'll love the GT102 if you want a single OTA that genuinely pulls double duty — sharp, colour-free visual views on casual nights and serious deep-sky imaging of galaxies and medium-scale nebulae when you commit to a full session. You're stepping up from a smaller scope, you already have an HEQ5-class mount, and you value the extra resolution and light grasp that 102mm delivers over 80mm. This isn't for you if you need the fastest possible wide-field imaging speed, if your mount can't handle 4+ kg of OTA plus camera gear, or if you want a ready-to-observe package out of the box.
Our verdict
These two are closer than most comparisons on this site. The spec differences are genuine — mount type, focal ratio — but neither is the wrong answer for a typical observer starting out.
If I had to choose between them: the Askar 80PHQ is the scope most people will be using regularly six months from now. The William Optics GT102 rewards you more once you know what you're doing — it's worth revisiting after your first year.
Askar 80PHQ
View Askar 80PHQ →William Optics GT102
View William Optics GT102 →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 80PHQ | William Optics GT102 |
|---|---|---|
Apertureⓘ The most important spec — bigger = more light = better views | 80mm | 102mm |
Focal Length Longer = more magnification potential | 448mm | 714mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/5.6 | f/7 |
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 PHQ quadruplet on all surfaces | Fully multi-coated FMC ED triplet on all air-to-glass surfaces |
How do you point it?
| Spec | Askar 80PHQ | William Optics GT102 |
|---|---|---|
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 80PHQ | William Optics GT102 |
|---|---|---|
Focuser Size 2" accepts wider eyepieces and gives better low-power views | 2" / 1.25" | 2" / 1.25" |
Focuser Type Rack-and-pinion is standard; Crayford and dual-speed are smoother | Dual-speed Crayford 2" (with 1.25" adapter) | Dual-speed Crayford 2" (10:1 reduction fine focus) |
Size & weight
| Spec | Askar 80PHQ | William Optics GT102 |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 2.8kg | 4kg |
Tube Length | 360mm | 565mm |
Tube Material | Aluminium | Aluminium, anodised |
What's in the box?
| Spec | Askar 80PHQ | William Optics GT102 |
|---|---|---|
Diagonal Tilts the eyepiece 90° for comfortable viewing — useful on refractors |
Blue highlight: Askar 80PHQ advantage · Amber highlight: William Optics GT102 advantage · Greyed cells: equal or subjective.