William Optics GT71 Triplet APO Refractor — image 1
William Optics

William Optics GT71 Triplet APO Refractor

A jewel-like 71mm FPL-53 triplet at a fast f/5.9, pinpoint, colour-free stars across a wide field in a tube light enough for the smallest trackers. Premium optics without the premium size.

88/ 100
Polaris Score
#1 of 8 imaging APO refractors
See the breakdown ↓
Aperture
71mm
Focal Length
420mm
Focal Ratio
f/5.9
Mount Type
None (OTA only)
Optical Design
Triplet APO
Weight
2.3 kg
From$1,198

Lowest in 90 daysLowest ever tracked

Price tracked by PolarisObserved 10 timesTracking since Mar 2026

Try in simulator →
What it's built forOpen these in the simulator →

This telescope was built for sweeping wide.

A short, fast refractor with a generous true field — the whole sword of Orion in one view, star fields that spill past the field stop. It rewards low power and dark skies far more than chasing magnification.

Widest true fieldsTack-sharp to the edge
The view people remember

The Double Cluster, side by side.

Two glittering knots of stars sharing one low-power field — a wide, effortless showpiece that rewards the biggest true field you can throw at it.

See Double Cluster through this telescope →
01What it's good at

What it's best at — and the trade-offs.

A three-element FPL-53 triplet all but eliminates false colour, stars image as clean white points to the edge.
Best at
✓A three-element FPL-53 triplet all but eliminates false colour, stars image as clean white points to the edge.
✓Fast f/5.9 gathers light quickly and frames large nebulae and galaxy fields in one shot.
✓At 2.3kg it rides the lightest star trackers, so the whole rig stays truly portable.
✓Beautiful, functional build: a rotating focuser, Bahtinov-mask cap and rings included.
Trade-offs
!Needs a matched flattener/reducer for corner-perfect stars on larger sensors (sold separately).
!Only 71mm, superb wide-field, limited on small faint objects.
!OTA only; a tracking mount and camera are extra.
!The fast focal ratio is less forgiving of camera tilt and spacing errors.
02In plain English

What These Numbers Mean

71mm · f/5.9 · 420mm FL
Aperture
71 mm
Under three inches of glass, so faint compact targets need long integration. What it does well is wide, clean fields with excellent colour correction, which is the point of a small triplet.
Focal length
420 mm
Wide field. The Andromeda Galaxy, the Pleiades, the North America Nebula and the Veil all frame on APS-C, covering most of the popular first-year imaging list.
Focal ratio
f/5.9
Fast enough for short exposures and short enough in focal length that small tracking errors stay invisible. That forgiveness is why this size and speed is such a common first imaging telescope.
Optical design
Triplet APO
Three elements keep bright stars free of the violet halo a doublet can show at this speed. Pair it with the matching flattener or reducer to keep corner stars round.
Weight
2.3 kg tube
About 5 lb, comfortably within star tracker limits with a camera attached. It packs into a backpack, which turns dark-sky trips into a habit rather than an expedition.
Mount
OTA only
No mount included, but very little is needed. A tracker or small equatorial produces round stars at 420 mm, keeping the total rig cost low.
03The Polaris Score

How it scores, and why.

88/100 · #1 of 8 imaging APO refractors
88/ 100
William Optics GT71 Triplet APO Refractor
#1 of 8 imaging APO refractors
Performance
90
Ease of use
80
Portability
90
Upgrade potential
82

Polaris weighs optical capability, how easy the scope is to live with, how portable it is, and how far it takes you before you outgrow it — not list price or brand.

04Who it's for

An honest fit check.

Imagers who want premium star colour without a heavy, expensive big apo.
Buy it if you
✓Imagers who want premium star colour without a heavy, expensive big apo.
✓Travellers pairing a quality apo with a small tracker.
✓Wide-field shooters after large nebulae and the Milky Way.
Look elsewhere if you
!Anyone needing reach on small targets, 420mm is deliberately wide.
!Deep-sky visual observers; a small apo is an imaging tool first.
!Budget buyers; triplet apos cost more per millimetre than doublets or reflectors.
05Build your rig

What to buy next — and where it leads.

7 pieces of gear, ordered by what changes the view most
Recommended upgrades
No fogging on long sessions★ Top pickPegasus Astro Multi-Channel Dew Controller

Stops dew from ending an imaging night.

Make nebulae popOptolong UHC Filter 2″

Lifts nebula contrast out of light-polluted skies.

Observe all night, no AA batteriesCelestron PowerTank Lithium

Runs the mount (and heaters) all night off one pack.

Growth path
Better tracking & light imagingSky-Watcher HEQ5 Pro SynScan GoTo Mount✓ Compatible

Commonly paired with this telescope

Portable astrophotographyZWO AM5N Harmonic Equatorial Mount✓ Compatible

Start capturing images of the Moon and planets

A versatile upgradeSky-Watcher Star Adventurer GTi GoTo EQ Mount Kit✓ Compatible

Commonly paired with this telescope

Start imagingZWO ASI533MC Pro

Start capturing images of the Moon and planets

Lunar & planetary
Excellent contrast
Deep-sky imaging
Strong with a flattener
Deep-sky visual
Wide, low-power views
06The numbers

Full specifications.

6 measured and stated values
Optics
Optical DesignTriplet APO
Aperture71mm
Focal Length420mm
Focal Ratiof/5.9
Mount & drive
Mount TypeNone (OTA only)
Physical
Weight2.3 kg
07Alternatives

For a different goal, start here.

2 alternatives, each mapped to the goal it wins at
cheaper

Sky-Watcher Evostar 80ED

A doublet with a little more aperture for much less, with slightly softer star colour.

→
flatter field

Askar FRA400C Quintuplet APO Refractor

A five-element astrograph with a built-in flat field and no separate corrector.

→
Also worth comparing
Askar 80PHQ Quadruplet Astrograph
Sharpstar / Askar
Askar 80PHQ Quadruplet Astrograph
Closest alternative at this size
Celestron EdgeHD 8
Celestron
Celestron EdgeHD 8
More capability for deeper views
SVBony SV555 54mm f/4.5 APO
SVBony
SVBony SV555 54mm f/4.5 APO
Smaller and easier to handle