Celestron Omni 56mm — image 1
Celestron

Celestron Omni 56mm

A 56mm Celestron Omni Plössl: a wide-field, low-power eyepiece for the biggest objects and rich star fields, from a clean, honest 52-degree Plössl that does one job well for very little money.

74/ 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 56mm 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
52°
Barrel Size
2"
Eye Relief
39mm
Focal Length
56mm
From$129.95

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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.

50° apparent field

At 52°, you are aware of the field edge, like looking down a short, comfortable tube.
Try this eyepiece on your own scope in the Simulator →
01What it's good at

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

Inexpensive enough to build a whole starter set around.
Best at
✓Inexpensive enough to build a whole starter set around.
✓Light and small; no strain on any focuser.
✓At 56mm it lands squarely in low power · wide field territory, exactly where wide star fields and large objects belong.
Trade-offs
!Short eye relief at the short focal lengths, uncomfortable below about 10mm.
!A 52-degree field feels narrow once you have looked through anything wider.
!Basic coatings and build compared with premium glass.
02In your telescope

One eyepiece. A different job in every scope.

9× in a small refractor, 36× in a long SCT

An eyepiece has no magnification of its own — the telescope decides. The same eyepiece becomes 9× and 5.8° of sky in a little refractor, or 36× 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
9×
True field
5.8°
Exit pupil
10.2 mm
9× across a 5.8° field at a 10.2mm exit pupil, a bright, low-power sweep for framing the largest objects.
8-inch Dobsonian
1200 mm · f/6
Magnification
21×
True field
2.5°
Exit pupil
9.3 mm
21× across a 2.5° field at a 9.3mm exit pupil, a bright, low-power sweep for framing the largest objects.
12-inch Dobsonian
1500 mm · f/5
Magnification
27×
True field
1.9°
Exit pupil
11.2 mm
27× across a 1.9° field at a 11.2mm exit pupil, a bright, low-power sweep for framing the largest objects.
8-inch SCT
2032 mm · f/10
Magnification
36×
True field
1.4°
Exit pupil
5.6 mm
36× across a 1.4° field at a 5.6mm exit pupil, a bright, low-power sweep for framing the largest objects.
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.

56mm FL · 52° AFOV · 2"
Focal lengthLowest power
56mm
About 21x in an 8 inch f/5.9 Dobsonian and 36x in an 8 inch SCT. In the f/10 SCT that produces a well-matched 5.6 mm exit pupil; in the fast Dobsonian it balloons past 9 mm, so most of the light would fall outside your pupil. This is an eyepiece for slow telescopes.
Apparent fieldClassic
52°
A traditional Plössl field, which at this focal length still yields the widest true field an SCT can practically reach. Simple designs also stay sharp across most of that field.
Eye reliefVery generous
39mm
Nearly four centimetres of eye relief is exceptionally comfortable, though it also means finding the correct eye position takes a moment. It is excellent for glasses wearers and for outreach.
BarrelRequires 2 inch focuser
2"
The 2 inch format is required to pass this field stop, so confirm your diagonal and focuser accept it. On an SCT this is the standard way to reach the lowest useful power.
OpticsSimple and sharp
Multi-coated
Few coated elements mean high transmission and minimal scatter. The design is straightforward; matching it to a slow enough telescope is what determines whether it performs well.
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.

56 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 (~34mm)
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.

74/100
74/ 100
Celestron Omni 56mm

Judged as a wide-field, low-power eyepiece for the biggest objects and rich star fields, it earns its score on simple four-element plössl optics: sharp on-axis and high in contrast. The comfortable eye relief lifts it further. A wide field is what this focal length is for, and it delivers.

Optical quality
70
Immersion
60
Comfort
94
Value
84

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 value on-axis contrast over a sprawling field.
Look elsewhere if you
!Anyone who has looked through a wide-field eyepiece and cannot go back to a 52-degree tunnel.
!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 Length56mm
Apparent Field52°
Comfort & handling
Eye Relief39mm
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 Omni Plössl 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 Omni 32mm

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

→
Cross-shop

Celestron X-Cel LX

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

→