Celestron Luminos 31mm — image 1
Celestron

Celestron Luminos 31mm

A 31mm Celestron Luminos: a wide-field, low-power eyepiece for the biggest objects and rich star fields, from an affordable 82-degree ultra-wide that puts the big-field experience within reach.

81/ 100
Polaris Score
Optical quality · Immersion · Comfort · Value
See the breakdown ↓
What it's for
Low power · wide fieldHigh power · narrow field

Low power · wide field. At 31mm this is a wide-field, low-power eyepiece for the biggest objects and rich star fields; it is not the eyepiece for high-power planetary detail.

Apparent Field
82°
Barrel Size
2"
Eye Relief
15mm
Focal Length
31mm
From$299.95

Lowest in 90 daysLowest ever tracked

Price tracked by PolarisObserved 101 timesTracking since Jul 2026

Try in simulator →
The spacewalk

You don’t look at a field.
You look into the sky.

Every number on the spec sheet matters less than one feeling: how much sky wraps around your eye. Widen the apparent field and watch the black edge of the eyepiece slip away.

82° apparent field

At 82°, the edge slips into your peripheral vision, you stop looking at a field and start looking into the sky.
Try this eyepiece on your own scope in the Simulator →
01What it's good at

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

15mm of eye relief and a large eye lens make the wide field easy to take in.
Best at
✓15mm of eye relief and a large eye lens make the wide field easy to take in.
✓Solid machined build with a twist-up eyecup.
✓At 31mm it lands squarely in low power · wide field territory, exactly where wide star fields and large objects belong.
Trade-offs
!Edge astigmatism and some field curvature show up in fast scopes below f/6.
!Heavy, especially the 2-inch long focal lengths.
!A little internal reflection on bright objects like the Moon.
02In your telescope

One eyepiece. A different job in every scope.

15× in a small refractor, 66× in a long SCT

An eyepiece has no magnification of its own — the telescope decides. The same eyepiece becomes 15× and 5.5° of sky in a little refractor, or 66× and a tight frame in a long SCT. Here’s what it does across common scopes.

Small apo refractor
480 mm · f/5.5
Magnification
15×
True field
5.5°
Exit pupil
5.6 mm
15× across a 5.5° field at a 5.6mm exit pupil, a bright, low-power sweep for framing the largest objects.
8-inch Dobsonian
1200 mm · f/6
Magnification
39×
True field
2.1°
Exit pupil
5.2 mm
39× across a 2.1° field at a 5.2mm exit pupil, a bright, low-power sweep for framing the largest objects.
12-inch Dobsonian
1500 mm · f/5
Magnification
48×
True field
1.7°
Exit pupil
6.2 mm
48× across a 1.7° field at a 6.2mm exit pupil, a bright, low-power sweep for framing the largest objects.
8-inch SCT
2032 mm · f/10
Magnification
66×
True field
1.2°
Exit pupil
3.1 mm
66× across a 1.2° field at a 3.1mm exit pupil, right in the deep-sky sweet spot, bright and easy on the eye.
Exit pupil is how wide the beam of light leaving the eyepiece is. Around 5–6 mm is bright and immersive under dark skies; push much past 6 mm and you waste light, and under light pollution a smaller exit pupil shows more contrast.
03In plain English

The numbers, in plain English.

31mm FL · 82° AFOV · 2"
Focal lengthLowest power
31mm
About 39x in an 8 inch f/5.9 Dobsonian and 66x in an 8 inch SCT. In the Dobsonian the exit pupil works out near 5.3 mm, which is close to ideal: the view is immersive and the full aperture is still being used.
Apparent fieldVery wide
82°
The widest true field in this family, which is what a long focal length and a very wide apparent field exist to produce. It is the eyepiece for sweeping the Milky Way and framing large nebulae in full.
Eye reliefComfortable
15mm
Enough for relaxed viewing without glasses during long scanning sessions, though the sheer field size means some eye movement to reach the edges.
BarrelRequires 2 inch focuser
2"
Only a 2 inch focuser can pass a field stop this large. This is also a substantial piece of glass, so on a Dobsonian expect to rebalance when you fit it.
OpticsWide-field value
Fully multi-coated
Coatings throughout maintain brightness across a very large optical train. In fast Newtonians a coma corrector meaningfully improves what this eyepiece shows at the field edge.
04What comes alive

The targets this eyepiece was born for.

The Veil Nebula, The North America Nebula, The Pleiades (M45), Milky Way star clouds, The…
The Veil NebulaComes alive
The Veil Nebula
With an OIII filter the lacework wraps across the field.
The North America NebulaExcellent
The North America Nebula
A wide, faint target that only fits at long focal length.
The Pleiades (M45)Comes alive
The Pleiades (M45)
The full cluster framed with room around every star.
Excellent
Milky Way star clouds
Sweeping the summer Milky Way at its richest.
The Andromeda Galaxy (M31)Excellent
The Andromeda Galaxy (M31)
The full span of the galaxy and its dust lanes.
The Double ClusterComes alive
The Double Cluster
Both clusters with a generous star field between them.
05Role in a collection

Where it sits in your eyepiece case.

Where it sits across 3 focal lengths

A good eyepiece collection isn’t a pile of glass — it’s two or three focal lengths that hand off from wide to tight. This is the anchor at the bottom of the ladder: the one you find and frame with. You buy it once, and it stays your low-power eyepiece for life.

31 mmThis one
Low power · wide field
Find, frame and sweep. Your widest true field and the lowest useful magnification, the eyepiece you reach for first.
Veil Nebula · Pleiades · Milky Way star clouds
13 mm
Medium power · the workhorse
Where most deep-sky objects look their best, galaxies, globulars and planetary nebulae at a comfortable scale.
M13 · Ring Nebula · most galaxies
7 mm
High power · detail
Planets, the Moon at the terminator, tight double stars and the smallest planetary nebulae. Steady-air nights only.
Jupiter · Saturn · lunar craters
06Build around it

What it pairs with.

The telescope · Pair it · Filter it
The telescope
What it goes into
Any 2-inch focuser
A 2-inch focuser or a 1.25-inch adapter; most Dobsonians and larger refractors qualify.
Fast, short scopes love this field
A fast Newtonian or refractor turns this focal length into a rich, wide sweep.
Pair it
What extends its range
A high-power eyepiece (~19mm)
Locate and frame with this one, then swap to high power for planets and small objects.
Filter it
What transforms the view
A UHC or OIII nebula filter
At low power this eyepiece frames big emission nebulae; a narrowband filter makes the Veil and North America jump out.
07The Polaris Score

How it scores, and why.

81/100
81/ 100
Celestron Luminos 31mm

Judged as a wide-field, low-power eyepiece for the biggest objects and rich star fields, it earns its score on a true 82-degree field for a fraction of the premium ultra-wides. The comfortable eye relief lifts it further. A wide field is what this focal length is for, and it delivers.

Optical quality
76
Immersion
93
Comfort
84
Value
78

Polaris weighs how well the eyepiece does the job it was designed for — optics, immersion, comfort and value — never list price or brand.

08Who it's for

An honest fit check.

Observers who want a wide-field, low-power eyepiece for the biggest objects and rich star…
Buy it if you
✓Observers who want a wide-field, low-power eyepiece for the biggest objects and rich star fields.
✓Anyone who observes in eyeglasses; the eye relief here is long enough to see the whole field.
✓Deep-sky observers chasing the most immersive, wrap-around field they can get at this price.
Look elsewhere if you
!Anyone chasing the absolute widest field, who should look at a 100-degree eyepiece.
!Grab-and-go observers watching every gram, since this is not the lightest option.
!Planetary specialists who want the last ounce of high-power contrast from an orthoscopic.
09The numbers

Full specifications.

4 measured and stated values
Optical
Focal Length31mm
Apparent Field82°
Comfort & handling
Eye Relief15mm
Fit & build
Barrel Size2"
Editor’s Take

Sweep it across a rich star field and the reason to own this focal length is obvious in a second. That is what the Luminos is for.

— The Skynocular verdict
10Alternatives

For a different goal, start here.

2 alternatives, each mapped to the goal it wins at
More magnification

Celestron Luminos 19mm

The same line at higher power, for planets and the smallest deep-sky detail.

→
Cross-shop

Explore Scientific 82°

A natural alternative at a nearby price point, if you want to compare field and feel before committing.

→