Telescope Comparison
Bresser Messier 8" Dobsonian vs Sky-Watcher Explorer 150PL
203mm versus 150mm — the aperture difference is the comparison.
First light
Bresser · 203mm · £349
The maximum-aperture visual reflector
- 203mm 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
- 17.5kg total — designed for a fixed garden or regular dark-sky site, not casual transport
Sky-Watcher · 150mm · £249
The sky-learner's equatorial scope
- 150mm newtonian reflector on a manual equatorial mount
- Good for: Moon, planets, bright star clusters and nebulae
- Setup includes rough polar alignment before observing — more steps than a simple alt-az
- Mount axes feel counterintuitive at first; users find they become natural after several sessions
- Keeps the door open for adding tracking motors and moving into astrophotography later
The full picture
The numbers that separate these two scopes — and what they mean at the eyepiece.
Aperture
Bresser Messier 8" Dobsonian gathers 1.8× more light. On bright targets — Moon, Saturn, Jupiter — you won't notice. On fainter targets — dim galaxies, faint globular clusters — the gap is real.
Focal length
Same focal length — identical magnification with any given eyepiece. Differences come from optical design and coatings.
Focal ratio
Bresser Messier 8" Dobsonian's faster f/5.91 delivers wider fields with any eyepiece — better for open clusters and large nebulae. Sky-Watcher Explorer 150PL's f/8 provides more magnification per eyepiece — better for fine planetary detail.
Mount type
Bresser Messier 8" Dobsonian's Dobsonian is immediately intuitive — no alignment, push to aim, observe. Sky-Watcher Explorer 150PL's equatorial mount requires polar alignment before each session but tracks the sky as Earth rotates, keeping objects centred.
Weight (OTA)
Sky-Watcher Explorer 150PL's optical tube is 6.4kg lighter. Relevant if you plan to use it on multiple mounts or carry the tube to dark-sky sites separately.
Optical design
Bresser Messier 8" Dobsonian is a DOBSONIAN; Sky-Watcher Explorer 150PL is a Newtonian reflector (mirrors, needs occasional collimation). Different optical formulas produce different strengths — reflectors give more aperture per pound; refractors give sharper contrast and require no collimation.
At the eyepiece
| Target | Bresser Messier 8" Dobsonian | Sky-Watcher Explorer 150PL |
|---|---|---|
| Planets | ||
| Moon | Excellent 203mm aperture resolves craters down to a few kilometres; the dual-speed focuser helps nail sharp focus at high power | Excellent 150mm aperture and f/8 focal ratio reward high-magnification lunar detail — craterlets, rilles, and shadow play along the terminator are superb. |
| Saturn | Excellent Cassini Division visible in steady seeing, cloud banding on the disc, and several moons including Titan easily spotted | Excellent 150mm aperture and 1200mm focal length put Cassini Division and cloud banding within reach in steady seeing. |
| Jupiter | Excellent Multiple cloud belts, Great Red Spot, and all four Galilean moons with shadow transits visible | Excellent Multiple cloud belts, the Great Red Spot, and Galilean moon shadows are visible at 150–200x. |
| Mars | Good Polar cap and dark surface features visible at opposition; the 1200mm focal length allows useful magnification with a short eyepiece | Good 150mm aperture shows the polar cap and dark surface markings near opposition — benefits from the long focal length for scale. |
Deep sky | ||
| Orion Nebula (M42) | Excellent Bright layered nebulosity with Trapezium resolved; 1200mm focal length crops the widest extent but detail in the core is superb | Good Bright core and Trapezium are striking, but the 1200mm focal length crops the outer nebulosity compared to a wider-field scope. |
| Andromeda Galaxy (M31) | Moderate 1200mm focal length shows the bright core and inner disc well, but the full 3° extent of the galaxy is cropped even with a wide-field 2" eyepiece | Moderate Bright core is easy, but the galaxy's full extent far exceeds the narrow field — only the central region is visible. |
| Open clusters | Moderate Compact clusters like the Double Cluster look fine, but large sprawling clusters like the Pleiades overfill the field at 1200mm | Moderate Larger clusters like the Double Cluster overfill the field at 1200mm; smaller, compact clusters fare better. |
| Globular clusters | Excellent 203mm resolves individual stars across the outer regions of M13 and M5; a defining strength of this aperture class | Good 150mm begins to resolve stars at the edges of M13 and M22 — a clear step up from smaller apertures. |
| Faint galaxies | Good Galaxy groups like the Leo Triplet and Virgo Cluster members are within reach; spiral arm hints visible in M51 under dark skies | Good 150mm gathers enough light to detect many Messier and brighter NGC galaxies, though detail is limited. |
| Milky Way / wide field | Not recommended 1200mm focal length is far too narrow for sweeping star fields — a wide-field refractor or binoculars serve this purpose better | Not recommended 1200mm focal length gives far too narrow a field for sweeping Milky Way star fields. |
Other | ||
| Double stars | Excellent 203mm aperture resolves doubles down to about 0.6 arcseconds; Dawes limit easily splits Albireo, the Double Double in Lyra, and many tighter pairs | Excellent 150mm aperture and f/8 focal ratio produce clean, high-contrast Airy discs — resolves pairs down to about 0.8 arcseconds. |
| Astrophotography (deep sky) | Not recommended No tracking means exposures beyond a second or two trail; manual Dobsonian mount is unsuitable for deep-sky imaging | Not applicable |
| Astrophotography (planetary) | Moderate Planetary video capture with a high-speed camera is feasible — 203mm aperture and 1200mm focal length give a usable image scale, but manual tracking makes it fiddly | Good 150mm aperture and 1200mm focal length suit webcam planetary imaging; the optional RA motor drive is strongly recommended to reduce drift. |
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
Bresser Messier 8" Dobsonian
- You'll set the base down, drop the tube in, and be observing within minutes — no polar alignment, no counterweights, no fumbling with latitude bolts in the dark, just point and look.
- You'll see things the 150PL simply cannot show you: M51's spiral arms instead of a featureless smudge, M13 with stars resolved across its face rather than just hinted at, and galaxies like M81/M82 with enough light to reveal their different structures — that extra 53mm of aperture is the difference between detecting an object and actually seeing detail in it.
- You'll learn to nudge the scope constantly at high power because nothing tracks for you, but the Dobsonian motion is intuitive — push it where you want — and the dual-speed Crayford focuser means nailing sharp planetary focus is genuinely satisfying rather than an exercise in frustration.
Sky-Watcher Explorer 150PL
- You'll spend your first few sessions learning polar alignment and the quirks of an equatorial mount, but once you've got it, the slow-motion controls let you track a planet or double star smoothly at 200× — something the Dobsonian's push-nudge approach makes far more fiddly.
- You'll get crisp, high-contrast planetary views that punch above what the aperture might suggest, because the f/8 focal ratio is forgiving of cheaper eyepieces and slight collimation errors — you don't need a coma corrector, and stars stay sharp across more of the field.
- You'll save £100 up front, and the equatorial mount gives you a future upgrade path to motorised tracking if you want to dabble in basic planetary imaging — something the Dobsonian mount simply doesn't offer without starting over.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Bresser
Bresser Messier 8" Dobsonian
The base has no fine altitude control out of the box — heavier eyepieces can cause the tube to droop, and most owners end up adding a tension spring mod to fix the balance.
At f/5.9, coma distortion is visible at the edges of wide-angle eyepieces, so if you want clean star fields across the whole view, you're looking at adding a coma corrector that costs nearly as much as the supplied eyepieces you'll also want to replace.
Collimation shifts with every car journey and sometimes between sessions — if you don't learn to collimate quickly and check it every time, your planetary views will be noticeably soft, and the scope's potential goes to waste.
Sky-Watcher
Sky-Watcher Explorer 150PL
The EQ3-2 mount is marginal for a tube this long — wind gusts or even touching the focuser can set off vibrations that take several seconds to dampen, which is especially annoying when you're trying to observe planets at 200×.
No motor drive is included, so despite having an equatorial mount, you're still manually correcting drift at high magnification — you get the setup complexity of an EQ mount without the tracking benefit unless you buy a motor separately.
The supplied 6×30 finder is dim and narrow, making it genuinely difficult to locate fainter targets — most owners replace it with a red-dot or Telrad almost immediately, adding an unplanned early cost.
Which is right for you?
Two different buyers. Two different right answers.
The maximum-aperture visual reflector
Bresser · Bresser Messier 8" Dobsonian
You want deep-sky observing to actually feel rewarding — not just ticking off faint smudges, but seeing spiral arms in galaxies and resolved stars in globular clusters. You don't mind a scope that takes up real space in the car and the living room, because on a clear night you want the most light-gathering power your budget allows. You're happy with a simple push-to setup that needs no power and no alignment procedure, and you'd rather spend your time at the eyepiece than wrestling with a mount. If you're a family, a club member, or a beginner who wants to be genuinely stunned by what's up there, this is where your £349 goes furthest.
The sky-learner's equatorial scope
Sky-Watcher · Sky-Watcher Explorer 150PL
You're drawn to the Moon and planets more than to faint fuzzies, and you want an evening where you park on Saturn's rings or split a tight double star and just savour the view. You'd rather learn the discipline of an equatorial mount now — polar aligning, using slow-motion cables — because you can see yourself adding a motor drive later and maybe trying planetary imaging. You're comfortable trading deep-sky reach for sharper, higher-contrast planetary views at a lower price, and you appreciate that the f/8 focal ratio means less fuss with collimation and no need for a coma corrector. This isn't for you if wide-field sweeping or galaxy hunting is the priority — but if the Moon and planets are your first love, the 150PL delivers where it matters.
Our verdict
At £249 versus £349, the Bresser Messier 8" Dobsonian costs 40% more. It delivers 53mm more aperture — a real and visible advantage on faint targets.
If budget is a genuine constraint, the Sky-Watcher Explorer 150PL will make you a happy observer. The Bresser Messier 8" Dobsonian's optical advantage on faint targets is real and you are unlikely to regret it if you can stretch. If I had to choose without knowing your situation: start with the Sky-Watcher Explorer 150PL, use it for a year, then upgrade knowing exactly what you want.
Bresser Messier 8" Dobsonian
View Bresser Messier 8" Dobsonian →Sky-Watcher Explorer 150PL
View Sky-Watcher Explorer 150PL →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 | Bresser Messier 8" Dobsonian | Sky-Watcher Explorer 150PL |
|---|---|---|
Apertureⓘ The most important spec — bigger = more light = better views | 203mm | 150mm |
Focal Length Longer = more magnification potential | 1200mm | 1200mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/5.91 | f/8 |
Optical Design The type of optics — each design has different strengths | Dobsonian | Newtonian Reflector |
Coatings Better coatings = more light transmission through the optics | Parabolic primary mirror, fully coated | Parabolic primary mirror with multi-coated optics |
How do you point it?
| Spec | Bresser Messier 8" Dobsonian | Sky-Watcher Explorer 150PL |
|---|---|---|
Mount Type The mechanical system that holds and moves the telescope | Dobsonian | Equatorial |
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 | Bresser Messier 8" Dobsonian | Sky-Watcher Explorer 150PL |
|---|---|---|
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 (2" with 1.25" adapter) | Rack and pinion |
Size & weight
| Spec | Bresser Messier 8" Dobsonian | Sky-Watcher Explorer 150PL |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 11.5kg | 5.1kg |
Total Weightⓘ Full setup including mount — this is what you lug to the car | 17.5kg | 14kg |
Tube Length | 1200mm | 900mm |
Tube Material | Steel | Steel |
What's in the box?
| Spec | Bresser Messier 8" Dobsonian | Sky-Watcher Explorer 150PL |
|---|---|---|
Eyepieces Included eyepieces — more is better, but quality matters more than quantity | 25mm and 10mm eyepieces | 25mm and 10mm Kellner |
Finder Scope Helps you locate areas of the sky before switching to the main eyepiece | 8x50 right-angle finder | 6x30 optical finder scope |
Diagonal Tilts the eyepiece 90° for comfortable viewing — useful on refractors |
Blue highlight: Bresser Messier 8" Dobsonian advantage · Amber highlight: Sky-Watcher Explorer 150PL advantage · Greyed cells: equal or subjective.