Apertura 102mm FCD-100 Doublet APO Classical Refractor — image 1
Apertura

Apertura 102mm FCD-100 Doublet APO Classical Refractor

A long, classical f/11 FCD-100 doublet built for one thing and doing it superbly: high-contrast, color-clean views of the Moon, planets and double stars. A visual refractor purist's tube, not a wide-field imager.

78/ 100
Polaris Score
# of 101 refractor
See the breakdown ↓
Aperture
102mm
Focal Length
1122mm
Focal Ratio
f/11
Mount Type
None (OTA only)
Optical Design
ED Doublet Refractor
Weight
4.8 kg
From$1,399.95

Lowest in 90 daysLowest ever tracked

Price tracked by PolarisObserved 54 timesTracking since Mar 2026

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What it's built forOpen these in the simulator →

This telescope lives for the planets.

An f/11 focal length built to magnify. Where fast scopes sweep wide, this one holds a single planet rock-steady at high power — a telescope for the patient observer on a steady night.

Sweet spot 80–130×Loves steady seeing
The view people remember

Saturn, with its rings tilted wide.

The one you call people outside to see — the rings standing clear of the planet, the Cassini Division a clean black line drawn around them.

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

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

The long f/11 focal ratio and FCD-100 ED glass give near-apo color correction, so bright stars and planet limbs stay clean and high-contrast.
Best at
✓The long f/11 focal ratio and FCD-100 ED glass give near-apo color correction, so bright stars and planet limbs stay clean and high-contrast.
✓102 mm at 1,122 mm delivers sharp, steady high-power views of lunar detail, planetary features and tight double stars.
✓A sealed refractor needs no collimation and holds its optics stable for years, with almost no cool-down fuss.
✓The dual-speed 2-inch rack-and-pinion focuser gives the fine control high magnification demands.
Trade-offs
!At f/11 it is slow, which rules out practical deep-sky astrophotography.
!The 1,122 mm long tube needs a sturdy mount and has real moment arm, so it is not a light travel scope.
!The narrow true field won't frame large objects like the Pleiades or the full Andromeda.
!Sold as an optical tube, so budget for a mount, diagonal and eyepieces.
02In plain English

What These Numbers Mean

102mm · f/11 · 1122mm FL
Aperture
102 mm
Four inches of unobstructed glass gathers roughly 210 times more light than your eye. That is enough for crisp lunar detail, the belts of Jupiter, Saturn's rings with the Cassini division on steady nights, and the brighter Messier clusters and nebulae. Faint galaxies stay small and grey; this scope trades reach for image quality.
Focal length
1122 mm
Long for a 4-inch refractor, which is exactly the point. It reaches 100x to 200x with ordinary eyepieces and no Barlow, so the Moon, planets and double stars sit naturally in the sweet spot. Wide fields are not its job: a 30 mm eyepiece still only gives about 37x.
Focal ratio
f/11
A slow focal ratio keeps colour error and coma essentially invisible and makes even inexpensive eyepieces perform well. The cost is a narrow field of view and dim, long exposures if you point it at deep-sky imaging. Treat it as a visual and planetary instrument first.
Optical design
FCD-100 ED doublet
Two elements with an FCD-100 ED front element, in a classical long-focus layout. At f/11 the doublet has an easy job correcting colour, so you get near-apochromatic sharpness for doublet money. A triplet buys you the same correction at a much faster ratio and a much higher price.
Weight
4.8 kg tube
About 10.5 lb of tube, but a long one. It is a one-hand carry to the mount, though the length gives it more leverage than the number suggests, so the mount matters more than the mass.
Mount
OTA only
No mount is included, and this tube's length punishes an undersized one. Budget for a solid alt-az or a mid-size equatorial rated well above 5 kg if you want steady views at 200x.
03The Polaris Score

How it scores, and why.

78/100 · #null of 101 refractor
78/ 100
Apertura 102mm FCD-100 Doublet APO Classical Refractor
# of 101 refractor
Performance
82
Ease of use
88
Portability
65
Upgrade potential
55

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.

Planetary, lunar and double-star observers
Buy it if you
✓Planetary, lunar and double-star observers
✓Refractor purists who want high contrast and clean color
✓Anyone wanting a low-maintenance high-power visual scope
Look elsewhere if you
!Wide-field and deep-sky imagers (f/11 is slow and the narrow field can't frame large targets)
!Grab-and-go travelers (the long tube needs a solid mount and some room)
!Buyers chasing maximum aperture per dollar (a Dobsonian shows far more faint deep sky)
05Build your rig

What to buy next — and where it leads.

7 pieces of gear, ordered by what changes the view most
Recommended upgrades
A sharper everyday view★ Top pickExplore Scientific 68deg 24mm

A wide 2-inch low-power eyepiece for framing and finding at this long focal length.

A sharper everyday viewCelestron X-Cel LX 12mm

A sharp mid-power eyepiece (~94x) for planets and the Moon.

Double your magnificationTele Vue 2x Barlow 1.25-inch

Doubles magnification for high-power planetary and double-star nights.

Growth path
Better tracking & light imagingCelestron Advanced VX (AVX) Equatorial Mount✓ Compatible

Commonly paired with this telescope

Portable astrophotographyZWO AM5N Harmonic Equatorial Mount✓ Compatible

Start capturing images of the Moon and planets

Permanent-setup astrophotographySky-Watcher EQ6-R Pro✓ Compatible

Commonly paired with this telescope

Start imagingZWO ASI2600MC Pro

Start capturing images of the Moon and planets

Lunar & planetary
Excellent contrast
Deep-sky imaging
Strong with a flattener
Deep-sky visual
Strong
06The numbers

Full specifications.

6 measured and stated values
Optics
Optical DesignED Doublet Refractor
Aperture102mm
Focal Length1122mm
Focal Ratiof/11
Mount & drive
Mount TypeNone (OTA only)
Physical
Weight4.8 kg