Baader Hyperion Aspheric 31mm — image 1
Baader Planetarium

Baader Hyperion Aspheric 31mm

A 31mm Baader Hyperion Aspheric: a wide-field, low-power eyepiece for the biggest objects and rich star fields, from a big-glass 72-degree low-power eyepiece at a price the premium brands cannot touch.

77/ 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
72°
Barrel Size
1.25" and 2"
Eye Relief
15mm
Focal Length
31mm
From$290

Lowest in 90 daysLowest ever tracked

Price tracked by PolarisObserved 102 timesTracking since Jul 2026

Try in simulator →
Where to buy

Verified 13h ago · prices tracked daily

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.

72° apparent field

At 72°, the black rim sits out at the corner of your attention rather than in front of you.
Try this eyepiece on your own scope in the Simulator →
01What it's good at

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

Long eye relief for such a low-power eyepiece.
Best at
✓Long eye relief for such a low-power eyepiece.
✓Dual 1.25-inch/2-inch barrel.
✓At 31mm it lands squarely in low power · wide field territory, exactly where wide star fields and large objects belong.
Trade-offs
!Aspheric, not fully corrected: the outer field shows aberration in fast scopes.
!Best treated as a low-cost wide finder, not a critical-sharpness eyepiece.
!Physically large and front-heavy.
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 4.8° 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
4.8°
Exit pupil
5.6 mm
15× across a 4.8° 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
1.8°
Exit pupil
5.2 mm
39× across a 1.8° 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
1.5°
Exit pupil
6.2 mm
48× across a 1.5° 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
1.1°
Exit pupil
3.1 mm
66× across a 1.1° 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 · 72° AFOV · 1.25" and 2"
Focal lengthLow power
31mm
About 39x in an 8 inch f/5.9 Dobsonian and 66x in an 8 inch SCT. In the Dobsonian that gives roughly a 5.3 mm exit pupil, close to ideal: bright and immersive while still using the full aperture.
Apparent fieldVery wide
72° in 2 inch mode
The headline 72 degrees applies when the eyepiece is used with its 2 inch barrel. Fitted with the supplied 1.25 inch barrel the field narrows to around 55 degrees, because the smaller barrel physically cannot pass a field stop that large.
Eye reliefComfortable
15mm
Comfortable without glasses; spectacle wearers will lose some of the outer field. That is a step down from the standard Hyperions, which is the compromise the aspheric wide-field design makes.
BarrelDual barrel
1.25" and 2" (both supplied)
It ships with both barrels, so it fits any telescope, but the two are not equivalent: use the 2 inch barrel to get the full field this eyepiece was designed for. In a scope limited to 1.25 inch you can still use it, at a noticeably narrower field.
OpticsAspheric wide-field
Multi-coatings
An aspheric element allows a wide, reasonably flat field without the element count of a premium design, which keeps both weight and price down. Fast telescopes will still show some edge softening.
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 1.25-inch focuser
Fits essentially every telescope made.
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.

77/100
77/ 100
Baader Hyperion Aspheric 31mm

Judged as a wide-field, low-power eyepiece for the biggest objects and rich star fields, it earns its score on a huge eye lens and wide field for the money, ideal for framing large deep-sky objects. The comfortable eye relief lifts it further. A wide field is what this focal length is for, and it delivers.

Optical quality
72
Immersion
82
Comfort
84
Value
80

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.
✓Observers who want a comfortably wide field without paying ultra-wide prices.
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 Field72°
Comfort & handling
Eye Relief15mm
Fit & build
Barrel Size1.25" and 2"
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 Hyperion Aspheric is for.

— The Skynocular verdict
10Alternatives

For a different goal, start here.

2 alternatives, each mapped to the goal it wins at
Wider, lower power

Baader Hyperion Aspheric 36mm

The same optics with more true field, for framing larger objects and finding your way around.

→
Cross-shop

Explore Scientific 68°

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

→