Baader Classic Ortho 10mm — image 1
Baader Planetarium

Baader Classic Ortho 10mm

A 10mm Baader Classic Ortho: a medium-high-power eyepiece for planets, globular cores and small planetary nebulae, from a four-element orthoscopic built for maximum contrast on planets and the Moon.

75/ 100
Polaris Score
Optical quality · Immersion · Comfort · Value
See the breakdown ↓
What it's for
Low power · wide fieldHigh power · narrow field

Medium-high power. At 10mm this is a medium-high-power eyepiece for planets, globular cores and small planetary nebulae; it is not meant for framing large deep-sky objects.

Apparent Field
50°
Barrel Size
1.25"
Eye Relief
9mm
Focal Length
10mm
From$108

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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 50°, 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.

Superb on-axis contrast and light throughput; four elements scatter almost nothing.
Best at
✓Superb on-axis contrast and light throughput; four elements scatter almost nothing.
✓Superb on-axis contrast and light throughput; four elements scatter almost nothing.
✓At 10mm it lands squarely in medium-high power territory, exactly where planetary and lunar detail lives.
Trade-offs
!A narrow 50-degree field; the object drifts through quickly on an undriven mount.
!Tight eye relief at short focal lengths, which is uncomfortable for eyeglass wearers.
!Not the eyepiece for large deep-sky objects that want a wide field.
02In your telescope

One eyepiece. A different job in every scope.

48× in a small refractor, 203× in a long SCT

An eyepiece has no magnification of its own — the telescope decides. The same eyepiece becomes 48× and 1.0° of sky in a little refractor, or 203× 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
48×
True field
1.0°
Exit pupil
1.8 mm
48× across a 1.0° field at a 1.8mm exit pupil, crisp medium power for galaxies, clusters and planetary nebulae.
8-inch Dobsonian
1200 mm · f/6
Magnification
120×
True field
25′
Exit pupil
1.7 mm
120× across a 25′ field at a 1.7mm exit pupil, crisp medium power for galaxies, clusters and planetary nebulae.
12-inch Dobsonian
1500 mm · f/5
Magnification
150×
True field
20′
Exit pupil
2.0 mm
150× across a 20′ field at a 2mm exit pupil, crisp medium power for galaxies, clusters and planetary nebulae.
8-inch SCT
2032 mm · f/10
Magnification
203×
True field
15′
Exit pupil
1.0 mm
203× across a 15′ field at a 1mm exit pupil, high power for planets, the Moon and tight doubles.
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.

10mm FL · 50° AFOV · 1.25"
Focal lengthHigh power
10mm
Gives 120x in an 8 inch f/5.9 Dobsonian and about 203x in an 8 inch SCT. A magnification usable on most nights rather than only the steadiest, which makes this the orthoscopic people reach for most often.
Apparent fieldClassic
50°
A narrow field by modern standards, traded deliberately for contrast. With only four elements there is very little glass to scatter light, which shows as cleaner detail on Jupiter's belts and the lunar surface.
Eye reliefTight
9mm
Nine millimetres means viewing without glasses and keeping your eye close. It is more workable than the 6 mm version but still not a relaxed position for a long session.
BarrelStandard
1.25"
The universal size, so it fits any telescope. A 50 degree field at 10 mm needs only a small field stop, so nothing is constrained by the format.
OpticsPlanetary specialist
Fully multi-coated
Full multi-coating on a simple Abbe design keeps transmission high and internal reflections almost absent. This is the eyepiece type planetary observers keep returning to after trying wider fields.
04What comes alive

The targets this eyepiece was born for.

Jupiter and its moons, Saturn, The Moon, M13 globular cluster, The Ring and Cat’s Eye…
Jupiter and its moonsComes alive
Jupiter and its moons
Belt detail with room to watch the Galilean moons shift.
SaturnComes alive
Saturn
Rings, the Cassini gap, and Titan in the same field.
The MoonExcellent
The Moon
A high-power tour of rilles, domes and crater chains.
M13 globular clusterExcellent
M13 globular cluster
The core starts to resolve into a spray of suns.
The Ring and Cat’s Eye nebulaeComes alive
The Ring and Cat’s Eye nebulae
Small planetary nebulae take real magnification well.
Excellent
Double stars
Clean, contrasty splits of colorful pairs.
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.

32 mm
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
10 mmThis one
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.
Longer focal length scopes reward it
The higher the scope’s focal length, the more planetary scale you get from this eyepiece.
Pair it
What extends its range
A low-power finder eyepiece (~16mm)
Use the long eyepiece to locate and frame, then drop in this one for detail.
Filter it
What transforms the view
A neutral-density Moon filter
Tames the glare of a bright gibbous Moon at high power so detail returns.
07The Polaris Score

How it scores, and why.

75/100
75/ 100
Baader Classic Ortho 10mm

Judged as a medium-high-power eyepiece for planets, globular cores and small planetary nebulae, it earns its score on superb on-axis contrast and light throughput; four elements scatter almost nothing. Tighter eye relief at this focal length is the main thing holding it back. It is honest about being a specialist, not an all-rounder.

Optical quality
86
Immersion
56
Comfort
58
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 medium-high-power eyepiece for planets, globular cores and small…
Buy it if you
✓Observers who want a medium-high-power eyepiece for planets, globular cores and small planetary nebulae.
✓Observers happy to take their glasses off at the eyepiece.
✓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.
!Eyeglass wearers, who will not comfortably reach the full field at this focal length.
!Anyone hoping to frame large nebulae; that is a job for a low-power eyepiece.
09The numbers

Full specifications.

4 measured and stated values
Optical
Focal Length10mm
Apparent Field50°
Comfort & handling
Eye Relief9mm
Fit & build
Barrel Size1.25"
Editor’s Take

Point it at a planet on a steady night and the case makes itself. This is where the Classic Ortho earns its keep.

— The Skynocular verdict
10Alternatives

For a different goal, start here.

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

Baader Classic Ortho 18mm

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

→
More magnification

Baader Classic Ortho 6mm

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 similar price point, if you want to compare field and feel before committing.

→