Telescope Comparison
Sky-Watcher Quattro 150P vs Ursa Major 6" f/8 Planetary Dobsonian
The Ursa Major 6" f/8 Planetary Dobsonian is a complete setup. The Sky-Watcher Quattro 150P needs a mount before it's usable.
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First light
Sky-Watcher · 150mm · £399
The custom-rig optical tube
- 150mm newtonian reflector — optical tube only, no mount included
- 750mm focal length at f/5
- Requires a compatible mount before you can observe anything
- Best for: observers who already own a suitable mount or are building a specific imaging rig
- Not a complete purchase — budget at least £100–300 extra for a mount before observing
Ursa Major · 152mm · £269
The maximum-aperture visual reflector
- 152mm Newtonian on a floor-standing Dobsonian alt-az rocker box
- Good for: full visual programme — planets, Moon, globular clusters, galaxies, nebulae
- No alignment required — set up and observe in under 10 minutes
- No motorised tracking — targets drift at high magnification as Earth rotates
- 20.9kg total — designed for a fixed garden or regular dark-sky site, not casual transport
The full picture
The numbers that separate these two scopes — and what they mean at the eyepiece.
Aperture
Effectively equal light-gathering. Aperture won't settle this comparison — the mount, focal ratio, and observing experience are what differ.
Focal length
Ursa Major 6" f/8 Planetary Dobsonian's longer focal length reaches higher magnification with the same eyepiece — better reach for planetary detail. Sky-Watcher Quattro 150P's shorter focal length gives a wider true field — better for large open clusters and extended nebulae.
Focal ratio
Sky-Watcher Quattro 150P's faster f/5 delivers wider fields with any eyepiece — better for open clusters and large nebulae. Ursa Major 6" f/8 Planetary Dobsonian's f/7.9 provides more magnification per eyepiece — better for fine planetary detail.
Mount type
Sky-Watcher Quattro 150P has no mount — add a compatible mount before you can observe. Ursa Major 6" f/8 Planetary Dobsonian is a complete ready-to-use system.
Weight (OTA)
Sky-Watcher Quattro 150P's optical tube is 4.4kg lighter. Relevant if you plan to use it on multiple mounts or carry the tube to dark-sky sites separately.
Optical design
Sky-Watcher Quattro 150P is a Newtonian reflector (mirrors, needs occasional collimation); Ursa Major 6" f/8 Planetary Dobsonian is a DOBSONIAN. Different optical formulas produce different strengths — reflectors give more aperture per pound; refractors give sharper contrast and require no collimation.
At the eyepiece
Both scopes · same aperture
Both are 151mm Newtonian reflectors — light gathering is identical. What you see through each depends on your eyepieces, your sky, and the steadiness of the atmosphere, not which scope you bought. Saturn's rings separate clearly from the disk; in good seeing, the Cassini Division — the dark gap between the A and B rings — is a genuine target at moderate magnification. Jupiter shows two equatorial cloud bands reliably, four Galilean moons changing position night to night. The Orion Nebula (M42) shows real nebulosity around the Trapezium, which splits into four stars at moderate magnification. The Andromeda Galaxy (M31) fills a wide-field eyepiece, the bright core distinct from the outer halo. What separates these scopes is the mount, the setup experience, and where you can use them — not what you see through them.
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
The Ursa Major 6" f/8 Planetary Dobsonian is a complete package — everything arrives in one box and you can observe the same day. The Sky-Watcher Quattro 150P is a bare optical tube that needs a separate compatible mount before you can point it at anything, adding significant cost and complexity. Unless you already own a suitable mount, the Ursa Major 6" f/8 Planetary Dobsonian is the practical choice.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Sky-Watcher
Sky-Watcher Quattro 150P
No mount included
You cannot observe until you buy a separate compatible mount — add at least £100–300 before you have a working telescope.
Nothing to look through on day one
Until a mount arrives, the optical tube is a piece of glass you cannot point at the sky.
Ursa Major
Ursa Major 6" f/8 Planetary Dobsonian
Objects drift out of view at high magnification
There is no tracking. At high magnification, targets drift across the field as Earth rotates and require regular manual nudging to keep them centred.
Too large for spontaneous outings
At 20.9kg total, getting this scope to a dark-sky site requires planning and ideally a second pair of hands. It suits a fixed garden setup or a dedicated trip, not an impulsive clear-night dash.
Which is right for you?
Two different buyers. Two different right answers.
The custom-rig optical tube
Sky-Watcher · Sky-Watcher Quattro 150P
You’ll love this if…
- You already own a compatible equatorial or alt-az mount — this is the optical tube you've specifically chosen to put on it
- You're building an imaging rig piece by piece and know exactly what you need at the end of a focuser
- Choosing an optical tube independently of the mount gives you more flexibility over your overall system
This will frustrate you if…
- You buy it without fully accounting for the mount — add at least £100–300 to the purchase price before you have a working telescope
- You expected a complete package and didn't realise this is a bare optical tube that cannot be used without a separate mount
The maximum-aperture visual reflector
Ursa Major · Ursa Major 6" f/8 Planetary Dobsonian
You’ll love this if…
- More aperture per pound is your main criterion — this design gives more light-gathering for your money than any other mount type at this price
- You plan to observe from a fixed garden or regular dark-sky site where you can set it up and leave it between sessions
- You prefer manual navigation — the Dobsonian rewards patient, hands-on observing and builds genuine sky knowledge over time
This will frustrate you if…
- You want to observe at high magnification without nudging the scope constantly — there is no tracking, and targets drift across the field as Earth rotates
- You want to take it to different locations easily — at this weight and size, it's a significant lift and benefits from a second pair of hands
- You want to take it out for spontaneous sessions — at this weight, getting it in and out of a car on your own requires planning and ideally a second pair of hands
Our verdict
This comparison has a catch: the Sky-Watcher Quattro 150P is a bare optical tube. You cannot use it without a separate mount — which adds meaningful cost and complexity. The Ursa Major 6" f/8 Planetary Dobsonian is a complete, ready-to-observe package.
For most buyers, the Ursa Major 6" f/8 Planetary Dobsonian is the right choice — you can observe the same night it arrives. The Sky-Watcher Quattro 150P makes sense if you already own a compatible mount, or are deliberately building a specific imaging setup piece by piece. If I had to choose for a first telescope: the Ursa Major 6" f/8 Planetary Dobsonian, without hesitation.
Sky-Watcher Quattro 150P
View Sky-Watcher Quattro 150P →Ursa Major 6" f/8 Planetary Dobsonian
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Deep field: Full specifications
Every data point, for those who want to go further.
Full specifications
Fields highlighted in blue or amber indicate the better value for that spec. Data is manufacturer-stated and may vary.
How much can it see?
| Spec | Sky-Watcher Quattro 150P | Ursa Major 6" f/8 Planetary Dobsonian |
|---|---|---|
Apertureⓘ The most important spec — bigger = more light = better views | 150mm | 152mm |
Focal Length Longer = more magnification potential | 750mm | 1200mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/5 | f/7.9 |
Optical Design The type of optics — each design has different strengths | Newtonian Reflector | Dobsonian |
Coatings Better coatings = more light transmission through the optics | Parabolic primary mirror, fully multi-coated | — |
How do you point it?
| Spec | Sky-Watcher Quattro 150P | Ursa Major 6" f/8 Planetary Dobsonian |
|---|---|---|
Mount Type The mechanical system that holds and moves the telescope | None (OTA only) | Dobsonian |
GoTo Computer-controlled pointing — finds any of thousands of objects automatically | ||
Tracking Motor keeps objects centred as the Earth rotates — essential for astrophotography |
The focuser
| Spec | Sky-Watcher Quattro 150P | Ursa Major 6" f/8 Planetary Dobsonian |
|---|---|---|
Focuser Size 2" accepts wider eyepieces and gives better low-power views | 2" | 1.25" |
Focuser Type Rack-and-pinion is standard; Crayford and dual-speed are smoother | Dual-speed Crayford (10:1 reduction) | 1.25" CNC Crayford |
Size & weight
| Spec | Sky-Watcher Quattro 150P | Ursa Major 6" f/8 Planetary Dobsonian |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 4.6kg | 9kg |
Total Weight Full setup including mount — this is what you lug to the car | — | 20.9kg |
Tube Length | — | 1100mm |
Tube Material | Steel | — |
What's in the box?
| Spec | Sky-Watcher Quattro 150P | Ursa Major 6" f/8 Planetary Dobsonian |
|---|---|---|
Eyepieces Included eyepieces — more is better, but quality matters more than quantity | — | 9mm and 25mm 1.25" Super-Plössl |
Finder Scope Helps you locate areas of the sky before switching to the main eyepiece | — | 6x30 straight-through |
Diagonalⓘ Tilts the eyepiece 90° for comfortable viewing — useful on refractors | — |
Blue highlight: Sky-Watcher Quattro 150P advantage · Amber highlight: Ursa Major 6" f/8 Planetary Dobsonian advantage · Greyed cells: equal or subjective.