Orion

Orion SkyScanner 135 mm Dobsonian Telescope

Name: Orion SkyScanner 135 mm Dobsonian Telescope
Brand: Orion
Price: 349.95 USD
Availability: InStock

A 135 mm f/8 Dobsonian built the way planetary scopes used to be built, with a long tube and a very small secondary mirror, which buys contrast on the Moon and planets that a fast 6-inch will not match. Orion shut down in 2024, so the stock on the shelf is the last of it.

75/ 100

Polaris Score

Performance · ease · portability · upgrade path

See the breakdown ↓

Aperture

135mm

Focal Length

1100mm

Focal Ratio

f/8

Mount Type

Dobsonian

Optical Design

Newtonian

Weight

14.8 kg

From$349.95

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Where to buy

High Point ScientificBest price$349.95→

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What it's built forOpen these in the simulator →

This telescope was built for your first nights out.

Light, simple, and forgiving — it shows the Moon, the bright planets, and the showpiece clusters without a manual. The kind of scope that actually gets used, because it is easy to carry out and easy to point.

Easy 30–120× viewsSet up in minutes

The view people remember

The Moon, raked by shadow.

Along the terminator the crater walls throw long shadows and the surface turns three-dimensional — the view almost everyone remembers from their first night at a telescope.

See The Moon through this telescope →

Where else it shines

Also excellent on

Saturn

Atmospheric bands or polar caps visible depending on the planet

Open view →

Easy first target

The Pleiades

Rich field — fainter members fill out the cluster

Open view →

Within reach

Orion Nebula

Stronger structure — embedded stars plus dark lanes within the core

Open view →

Rewards a dark sky

Andromeda Galaxy

Definite galaxy shape — core stands out against the sky

Open view →

✦

It will show you the sky, not photograph it, and you may outgrow its aperture within a year or two. That is exactly the point.

01What it's good at

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

The 38 mm secondary blocks only 28 percent of the aperture across, under 8 percent by area, which is low for a Newtonian and shows up directly as…

Best at

✓The 38 mm secondary blocks only 28 percent of the aperture across, under 8 percent by area, which is low for a Newtonian and shows up directly as planetary contrast

✓f/8 is forgiving in a way fast Dobsonians are not: coma is negligible, collimation tolerance is wide, and cheap eyepieces perform close to their best

✓1100 mm of focal length reaches 110x with the supplied 10 mm eyepiece, so it arrives at planetary magnification without buying anything

✓A full floor base rather than a tabletop, so it does not need furniture to be usable

Trade-offs

!The focuser takes 1.25-inch eyepieces only, which caps the widest possible true field near 1.4 degrees and rules out 2-inch wide-field eyepieces permanently

!At $349.95 it is priced against a 150 mm Heritage, which gathers 23 percent more light for the same money

!32.6 lb in two pieces with a 40-inch tube, so it is a two-trip carry rather than a grab-and-go

!Orion ceased trading in 2024, so once this stock sells through there is no warranty, no spare focuser and no support

02In plain English

What These Numbers Mean

135mm · f/8 · 1100mm FL · Dobsonian

Aperture

135 mm (5.3 inch)

Gathers roughly 370 times the light of your eye and resolves to 0.86 arcseconds, which is enough to split most double stars a beginner will chase and to show Cassini's Division in Saturn's rings on a steady night. It is a real step past a 100 mm scope, though a 6-inch gathers 23 percent more and a 8-inch nearly two and a half times as much.

Focal length

1100 mm

Long for this aperture, and that is the whole point of the design. The supplied 10 mm eyepiece already gives 110x without a Barlow, where a short tabletop scope would need a 4 mm eyepiece to get there. The cost is field width: wide targets like the Pleiades or the Andromeda galaxy will not fit.

Focal ratio

f/8

Slow optics are easy optics. Coma at the field edge is negligible instead of obvious, collimation errors are forgiven rather than punished, and inexpensive eyepieces show tight stars corner to corner. This is why an f/8 scope often outperforms a faster one of the same size on planets with the eyepieces people actually own.

Optical design

Newtonian, 38 mm secondary

The secondary mirror obstructs 28 percent of the aperture across and under 8 percent of its area, which is small for a Newtonian and unusual at this price. A large obstruction drains contrast from fine planetary detail; keeping it this small is the single design decision that makes this a planetary telescope rather than a general-purpose one.

Focuser

1.25 inch rack and pinion

This is the specification that limits the telescope, and it cannot be upgraded away. A 1.25-inch barrel caps the field stop near 27 mm, so at 1100 mm focal length the widest true field you can ever reach is about 1.4 degrees. Everything sharp about this scope happens above 40x; below that it simply cannot go wide.

Weight

14.8 kg total

32.6 lb split into an 8.9 lb tube and a 23.6 lb base, with the tube 40 inches long. You carry it out in two trips and assemble nothing, which is manageable for a garden but not for a hike. It stands on the ground at a comfortable height, so unlike a tabletop scope it needs no furniture.

03The Polaris Score

How it scores, and why.

75/100

75/ 100

Orion SkyScanner 135 mm Dobsonian Telescope

Performance

Ease of use

Portability

Upgrade potential

Polaris weighs optical capability, how easy the scope is to live with, how portable it is, and how far it takes you before you outgrow it — not list price or brand.

04Who it's for