SVBony

SVBony Redline 6mm Ultra Wide Angle

Name: SVBony Redline 6mm Ultra Wide Angle
Brand: SVBony
Price: 40.99 USD
Availability: InStock

A 6mm with almost 15mm of eye relief, which no Plossl of this power can offer. Sharp on axis, but prone to ghosting and to blacking out if your eye drifts off centre.

72/ 100

Polaris Score

Optical quality · Immersion · Comfort · Value

See the breakdown ↓

What it's for

Low power · wide fieldHigh power · narrow field

A high power eyepiece. In most telescopes it lands between 80x and 340x, which is planetary and double star territory, plus the smallest planetary nebulae. It is the wrong eyepiece for anything large or faint, and on many nights the atmosphere will not support the top of that range at all.

Apparent Field

68°

Barrel Size

1.25"

Eye Relief

14.8mm

Focal Length

6mm

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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.

68° apparent field

At 68°, 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.

A built-in Barlow group ahead of the eye lens keeps eye relief near 15mm, where a conventional 6mm gives you six and is genuinely uncomfortable.

Best at

✓A built-in Barlow group ahead of the eye lens keeps eye relief near 15mm, where a conventional 6mm gives you six and is genuinely uncomfortable.

✓On axis it is sharp, and on a steady night it will show Cassini's division and Jupiter's belt structure as well as eyepieces costing five times more.

✓It costs less than a filter, which makes the high power slot in a first eyepiece set almost free.

Trade-offs

!Kidney beaning: the exit pupil is small and the field darkens on one side if your eye moves off the axis. It is a learned skill, not a defect, but it is real.

!Ghosting and internal reflections when a bright object sits just inside or outside the field, a consequence of basic blackening and coatings.

!The measured apparent field at this focal length comes out nearer 63 degrees than the 68 the family is sold under, so it is the narrowest view of the four despite the identical label.

02In your telescope

One eyepiece. A different job in every scope.

80× in a small refractor, 339× in a long SCT

An eyepiece has no magnification of its own — the telescope decides. The same eyepiece becomes 80× and 51′ of sky in a little refractor, or 339× 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

80×

True field

51′

Exit pupil

1.1 mm

In a 480mm apo refractor this gives 80x across 51 arcminutes with a 1.1mm exit pupil, a comfortable high power for a small scope and about as far as a 480mm instrument usefully goes on planets.

8-inch Dobsonian

1200 mm · f/6

Magnification

200×

True field

20′

Exit pupil

1.0 mm

In an eight inch Dobsonian it lands on 200x with a 20 arcminute field, which is genuine planetary magnification and roughly the maximum a typical night's seeing will carry.

12-inch Dobsonian

1500 mm · f/5

Magnification

250×

True field

16′

Exit pupil

1.2 mm

In a twelve inch Dobsonian it reaches 250x with a 1.2mm exit pupil, bright enough to hold detail but demanding both good seeing and a mount you can nudge smoothly at that power.

8-inch SCT

2032 mm · f/10

Magnification

339×

True field

12′

Exit pupil

0.6 mm

In an eight inch Schmidt-Cassegrain it produces 339x with an exit pupil of just 0.6mm, which is past the point of diminishing returns on all but the steadiest nights, and where the tight eye placement is hardest to manage.

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.

6mm FL · 68° AFOV · 1.25"

Eye reliefRemarkable for a 6mm

14.8 mm

This is how far behind the lens your eye can sit and still see the whole field. A conventional 6mm Plossl gives you about four to six millimetres, which in practice means your eyelashes on the glass and your breath fogging it. Nearly fifteen millimetres here comes from a small Barlow group built in ahead of the eye lens, and it is the single feature that makes this focal length usable rather than endured. SVBONY's own spec table prints 17mm for all four focal lengths in the family, which is a copy and paste error; this figure comes from the identical Agena badged version, which publishes them individually.

Eye placementNeeds a still head

Small exit pupil, unforgiving

The exit pupil is the small cone of light leaving the eyepiece, and at 6mm in a fast scope it is around one millimetre across. Your pupil has to sit inside it. Drift a couple of millimetres off axis and one side of the field goes dark, which observers call kidney beaning or blackout. Nothing is broken when this happens. It does mean this is not an eyepiece you can look through casually, and it is the most common complaint about this focal length.

Apparent fieldNarrowest in the set

68° claimed, nearer 63° measured

This is how large the circle of view appears, and it is worth knowing that the four focal lengths in this family do not all deliver the field the shared label promises. Independent measurement puts this one around 63 degrees while the 9mm comes out near 70. It is still far wider than the 52 degree Plossl it replaces, but if you buy two of the set expecting matched fields, they will not quite match.

Magnification rangeHigh power

80x to 340x

What this focal length actually gives you depends entirely on the telescope. In a small refractor it is a useful 80x. In an eight inch Schmidt-Cassegrain it is 339x, which is more magnification than the atmosphere supports on most nights from most locations. Before blaming the eyepiece for a mushy view of Jupiter, check whether the air was steady enough to carry the power you asked of it.

Optical designWith a built-in Barlow

5 elements in 3 groups

The family is a derivative of the classic Konig formula, but the 6mm and 9mm add a Barlow group that both shortens the effective focal length and pushes the eye relief out. It is the same trick premium manufacturers use for the same reason. Here it is executed cheaply, which buys the comfort and costs the stray light control.

04What comes alive

The targets this eyepiece was born for.

Saturn, Jupiter's cloud belts, Lunar craters at the terminator, Mars near opposition, Tight…

Comes alive

Saturn

At 200x and up the Cassini division is a clean gap and the shadow of the globe falls across the rings.

Comes alive

Jupiter's cloud belts

The two main belts, festoons along their edges, and the Great Red Spot when it faces you.

Comes alive

Lunar craters at the terminator

Crater walls, central peaks and rilles, with shadows long enough to read the relief.

Excellent

Mars near opposition

The polar cap and the larger dark markings, on the handful of nights each opposition when the air cooperates.

Excellent

Tight double stars

Splits pairs under an arcsecond when the seeing is calm, and this is where the on-axis sharpness shows honestly.

Excellent

The Ring Nebula (M57)

Small planetaries take magnification well. The ring tightens and the background sky goes darker around it.

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

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

6 mmThis one

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 this focal length works

An f/8 or slower refractor

A larger exit pupil makes the tight eye placement much more forgiving, and this is the easiest home for the eyepiece.

An eight inch Dobsonian

200x is close to the practical ceiling for most nights, which makes this a well matched planetary eyepiece rather than an overreach.

Pair it

What to own alongside

SVBony Redline 20mm Ultra Wide Angle

The wide field end of the same set. Between 6mm and 20mm you have the range covered for under ninety dollars.

A steady mount or a smooth Dobsonian base

At 200x and up, a mount that shakes for three seconds after every nudge will cost you more detail than any eyepiece upgrade returns.

Filter it

What changes the view

A Moon filter

The Moon at 200x in an eight inch scope is bright enough to be genuinely uncomfortable and to cost you your dark adaptation.

No nebula filter

A UHC or OIII does nothing useful at this power. Nebula filters belong on the low power eyepieces in the set.

07The Polaris Score

How it scores, and why.

72/100

72/ 100

SVBony Redline 6mm Ultra Wide Angle

Judged against the alternative at this price, which is a 6mm Plossl with six millimetres of eye relief, this is the more usable eyepiece by a wide margin. It scores below its 9mm and 20mm siblings because the ghosting and the tight eye placement are real and are noticed on the first night, not just by pixel peepers. Good value, with conditions you should know before you buy.

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.

Anyone who wants real planetary magnification without spending more on the eyepiece than…

Buy it if you

✓Anyone who wants real planetary magnification without spending more on the eyepiece than they did on half the telescope.

✓Observers who have tried a 6mm Plossl, found it physically unpleasant to look through, and assumed that was just how high power works.

✓Owners of slower telescopes at f/8 and beyond, where the exit pupil stays large enough to be forgiving and the design is at its easiest.

✓Anyone assembling the classic three eyepiece budget kit and wanting the high power slot filled cheaply.

Look elsewhere if you

!Observers who cannot keep their head still at the eyepiece, since the small exit pupil punishes any drift with a darkened field.

!Anyone observing from a location where the seeing rarely supports over 200x, which describes most suburban skies on most nights.

!Owners of fast telescopes who want the best of this family, since the 9mm is the focal length that handles fast optics well and this one is a step behind it.

!Observers sensitive to stray light, because a bright planet just outside the field will throw a visible ghost.

09The numbers

Full specifications.

7 measured and stated values

Optical

Focal Length6mm

Apparent Field68°

CoatingsFully multi-coated

Comfort & handling

Eye Relief14.8mm

Fit & build

Barrel Size1.25"

More

lens design5 elements in 3 groups

weight g133

Editor’s Take

The reason this eyepiece exists in a form worth buying is a small Barlow group sitting ahead of the eye lens. It lengthens the eye relief that a 6mm would otherwise not have, and it is why you can use this focal length without pushing your eyelashes into the glass. The same trick costs you something. The exit pupil is small and unforgiving, so if your eye wanders off the axis the field darkens on one side, an effect observers call kidney beaning. You learn to hold your head still, and then it is a very cheap way into high power.