Houdini Telescopes

Houdini 20mm 86° Coma-Correcting

Name: Houdini 20mm 86° Coma-Correcting
Brand: Houdini Telescopes
Price: 429 USD
Availability: InStock

The first eyepiece with a coma corrector built into the barrel, this 20mm shows a fast Dobsonian pinpoint stars across a huge 86° field with no separate Paracorr. It is the low-power wide-field to own if you observe at f/5 or faster.

86/ 100

Polaris Score

Optical quality · Immersion · Comfort · Value

See the breakdown ↓

What it's for

Low power · wide fieldHigh power · narrow field

At 20mm this is a low-power, wide-field eyepiece for framing large nebulae and star fields at a bright exit pupil. It is not a planetary or high-resolution eyepiece, and its coma correction is meant for fast Newtonians, not slow SCTs or refractors.

Apparent Field

86°

Barrel Size

Eye Relief

20mm

Focal Length

20mm

From$429

Lowest in 90 daysLowest ever tracked

Price tracked by PolarisObserved 91 timesTracking since Jul 2026

Try in simulator →

Where to buy

Agena AstroProductsPartnerBest price$429→

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.

86° apparent field

At 86°, 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.

It is the only eyepiece with a coma corrector integrated into the optics, so stars stay pinpoint to the edge of the 86° field in a fast Newtonian with…

Best at

✓It is the only eyepiece with a coma corrector integrated into the optics, so stars stay pinpoint to the edge of the 86° field in a fast Newtonian with nothing bolted to the focuser.

✓For a Dob owner it collapses two purchases, a coma corrector and a wide eyepiece, into one, and the flat, low-distortion field holds magnification constant across the view.

✓The 20mm eye relief and folding rubber eyecup make the enormous field genuinely comfortable to take in, glasses on or off.

Trade-offs

!The coma correction does nothing in SCTs, Maksutovs, and refractors, so those owners pay for a feature their scope will never use.

!At a 2-inch barrel and 1.26 pounds it is a heavy eyepiece that needs a 2-inch focuser and can unbalance a light tabletop Dob.

!Houdini is a young brand without the decades-long coating and resale track record of Tele Vue or Pentax.

02In your telescope

One eyepiece. A different job in every scope.

24× in a small refractor, 102× in a long SCT

An eyepiece has no magnification of its own — the telescope decides. The same eyepiece becomes 24× and 3.6° of sky in a little refractor, or 102× 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

24×

True field

3.6°

Exit pupil

3.6 mm

At 24× across a 3.6° field it is a gorgeous low-power sweep at a 3.6mm exit pupil, though a refractor has no coma for the correction to fix.

8-inch Dobsonian

1200 mm · f/6

Magnification

60×

True field

1.4°

Exit pupil

3.3 mm

At 60× the 1.4° field frames whole clusters, and at f/6 the built-in correction keeps the edge stars tight where a plain wide-field would start to smear them.

12-inch Dobsonian

1500 mm · f/5

Magnification

75×

True field

1.1°

Exit pupil

4.0 mm

This is the eyepiece's element: at f/5 coma is strong, and 75× holds pinpoint stars corner to corner across a 1.15° field that an ordinary eyepiece could never keep clean.

8-inch SCT

2032 mm · f/10

Magnification

102×

True field

51′

Exit pupil

2.0 mm

At 102× in an f/10 SCT the view is sharp but the coma correction does nothing here, so you are paying for a feature this scope never needed.

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.

20mm FL · 86° AFOV · 2"

Apparent fieldUltra-wide

86°

The view spans 86 degrees, a porthole so wide its edge sits out past your peripheral vision, the immersive spacewalk look.

Coma correctionUnique

Built-in

A coma corrector is built into the barrel, so stars stay pinpoint to the very edge in fast Newtonians without adding a separate Paracorr to your focuser.

Eye reliefGlasses-friendly

20 mm

Twenty millimeters of eye relief plus a folding eyecup means you take in the whole 86 degrees comfortably, with or without glasses.

Focal lengthLow power

20 mm

At 20mm this is a low-power, wide-field eyepiece, the one you reach for to frame big nebulae and star fields, not to chase planetary detail.

Barrel & weightHeavy

2" · 1.26 lb

The 2-inch barrel and 1.26-pound heft need a 2-inch focuser and can tip the balance of a light Dob.

04What comes alive

The targets this eyepiece was born for.

Pleiades (M45), Double Cluster, Veil Nebula, Andromeda Galaxy (M31), North America Nebula…

Comes alive

Pleiades (M45)

The whole cluster and its brightest stars sit in one 86° frame with pinpoint edges.

Comes alive

Double Cluster

Both clusters together, framed with sharp stars corner to corner in a fast Dob.

Comes alive

Veil Nebula

Low power and a wide true field trace the full arc of the Veil, sharp to the edge, with an OIII filter.

Excellent

Andromeda Galaxy (M31)

The galaxy's full span and both companions fit the wide, bright low-power field.

Excellent

North America Nebula

The large, faint shape needs exactly this low-power wide field to show its outline.

Excellent

Beehive Cluster (M44)

A big open cluster that fills the low-power field with sharp points of light.

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.

20 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

Where it earns its price

A fast Newtonian or Dobsonian (f/4–f/6)

The steeper the light cone, the more the built-in coma correction matters

Pair it

What extends its range

Houdini 12mm 86° Coma-Correcting

The higher-power sibling for tighter framing and small deep-sky detail

Filter it

What transforms the view

Optolong UHC Filter 2″

Emission nebulae like the Veil and North America pop across the wide low-power field

07The Polaris Score

How it scores, and why.

86/100

86/ 100

Houdini 20mm 86° Coma-Correcting

It earns its standing on a genuinely novel idea executed well: built-in coma correction that keeps stars sharp to the edge of a huge field in exactly the fast scopes where ordinary wide-fields fall apart, with eye relief comfortable enough to actually use the whole view. It gives up ground only on an unproven brand track record and on being wasted effort in scopes that have no coma to correct.

Optical quality

Immersion

Comfort

Value

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.

Owners of fast Newtonians and Dobsonians (roughly f/4 to f/6) who want sharp edge stars…

Buy it if you

✓Owners of fast Newtonians and Dobsonians (roughly f/4 to f/6) who want sharp edge stars without buying a separate coma corrector.

✓Wide-field deep-sky observers who frame large nebulae, star fields, and big open clusters at low power.

✓Eyeglass wearers who want a comfortable 2-inch low-power eyepiece they can use with the whole field visible.

✓Dob owners deciding between a Paracorr plus a premium eyepiece and a single glass that does both jobs.

Look elsewhere if you

!Owners of SCTs, Maksutovs, or refractors, which have essentially no coma, so the built-in correction is a feature you pay for but cannot use.

!Observers on a budget, since at street price this is premium-eyepiece territory.

!Anyone who already owns a Paracorr and a favorite wide-field, who would be paying twice for the same result.

!Owners of scopes with only a 1.25-inch focuser, which this 2-inch barrel will not fit.

09The numbers

Full specifications.

4 measured and stated values

Optical

Focal Length20mm

Apparent Field86°

Comfort & handling

Eye Relief20mm

Fit & build

Barrel Size2"

Editor’s Take

For a generation, owning a fast Dob meant accepting comet-shaped edge stars or bolting a $500 Paracorr onto the focuser. The Houdini quietly folds that correction into the eyepiece itself, and the first time the outer edge of an 86° field stays needle-sharp in an f/5 scope, the trick feels a little like magic. The name fits.