Apertura
Apertura 90 mm Triplet Refractor with Field Flattener and Hard Case
A 90mm FPL-53 triplet apo that ships with a field flattener and a hard case, pinpoint, colour-free stars and a wide flat field, the forgiving way into serious deep-sky imaging.
87/ 100
Aperture
90mm
Focal Length
540mm
Focal Ratio
f/6
Mount Type
None (OTA only)
Optical Design
Triplet APO
Weight
4.9 kg
From$1,799.95
Lowest in 90 daysLowest ever tracked
Price tracked by PolarisObserved 61 timesTracking since Mar 2026
01What it's good atWhat it's best at — and the trade-offs.
An FPL-53 triplet controls false colour so stars image as clean white points, not blue-fringed blobs.
01What it's good at
What it's best at — and the trade-offs.
An FPL-53 triplet controls false colour so stars image as clean white points, not blue-fringed blobs.
Best at
✓An FPL-53 triplet controls false colour so stars image as clean white points, not blue-fringed blobs.
✓Comes with a matched field flattener, the corner-sharpening lens most refractors make you source separately.
✓A refractor has no collimation and no cooldown fuss; it is the most beginner-forgiving imaging optic.
✓The included hard case makes it a true travel-and-image rig.
Trade-offs
!Only 90mm of aperture, great for wide fields, limited on small, faint targets.
!OTA only; it still needs a tracking equatorial mount and a camera.
!At f/6 it is slower than the fast astrographs, so exposures run longer.
!A doublet or the fast astrographs beat it on pure speed or aperture at similar money.
02In plain EnglishWhat These Numbers Mean
90mm · f/6 · 540mm FL
02In plain English
What These Numbers Mean
90mm · f/6 · 540mm FL
Aperture
90 mm
A useful step up from the common 72 mm starter refractors: roughly 55 percent more light, which shortens exposures and pulls fainter nebulosity out of the same sky. Visually it handles the Moon and planets well and shows the brighter deep-sky objects with real definition.
Focal length
540 mm
Wide-field but not extreme. On APS-C it frames the Veil complex, the Rosette or the Heart Nebula comfortably, and still gives enough image scale for the larger galaxies. This is one of the most useful all-round imaging focal lengths.
Focal ratio
f/6
Fast enough for practical exposure times under suburban skies and forgiving of guiding error. Combined with the included flattener it delivers a flat, well corrected field across a full-frame-adjacent sensor.
Optical design
Air-spaced triplet APO
Three elements correct colour across the visible spectrum, so bright stars stay white rather than fringed and blue channels stay sharp in imaging. A triplet is heavier and cools more slowly than a doublet, which is the price of that correction.
Weight
4.9 kg tube
Around 11 lb before rings, camera and guiding. That is still portable, but it pushes you past star-tracker territory and into a proper equatorial mount.
Mount
OTA only, flattener and case included
The bundle covers the optical accessories most people buy separately, but not the mount. Plan on an equatorial rated for at least 10 kg once camera and guide scope are attached.
03The Polaris ScoreHow it scores, and why.
87/100 · #2 of 8 imaging APO refractors
03The Polaris Score
How it scores, and why.
87/100 · #2 of 8 imaging APO refractors
87/ 100
Apertura 90 mm Triplet Refractor with Field Flattener and Hard Case
#2 of 8 imaging APO refractors
Performance89
Ease of use78
Portability82
Upgrade potential83
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 forAn honest fit check.
Beginner-to-intermediate imagers who want a forgiving, high-quality first apo.
04Who it's for
An honest fit check.
Beginner-to-intermediate imagers who want a forgiving, high-quality first apo.
Buy it if you
✓Beginner-to-intermediate imagers who want a forgiving, high-quality first apo.
✓Travellers who need a compact, cased rig that survives the trip.
✓Anyone tired of collimating a fast Newtonian who wants pinpoint stars with less fuss.
Look elsewhere if you
!Planetary and small-galaxy imagers who need long focal length and big aperture.
!Deep-sky visual observers chasing the faintest targets, 90mm is modest for the eye.
!Budget buyers; a small apo costs more per millimetre of aperture than a reflector.
05Build your rigWhat to buy next — and where it leads.
7 pieces of gear, ordered by what changes the view most
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.
$259.90View details →
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.
$99.95View details →
Growth path
Better tracking & light imagingCelestron Advanced VX (AVX) Equatorial Mount✓ Compatible
Commonly paired with this telescope
$1,099View details →
Portable astrophotographyZWO AM5N Harmonic Equatorial Mount✓ Compatible
Start capturing images of the Moon and planets
$2,299View details →
Permanent-setup astrophotographySky-Watcher EQ6-R Pro✓ Compatible
Commonly paired with this telescope
$2,250View details →
Start imagingZWO ASI2600MC Pro
Start capturing images of the Moon and planets
$1,499View details →
06The numbersFull specifications.
6 measured and stated values
06The numbers
Full specifications.
6 measured and stated values
Optics
Optical DesignTriplet APO
Aperture90mm
Focal Length540mm
Focal Ratiof/6
Mount & drive
Mount TypeNone (OTA only)
Physical
Weight4.9 kg
07AlternativesFor a different goal, start here.
2 alternatives, each mapped to the goal it wins at
07Alternatives
For a different goal, start here.
2 alternatives, each mapped to the goal it wins at
