Telescope Comparison
Celestron CGEM II 8 SCT vs Celestron CPC 800
The price gap is real. The question is whether the extra capability is worth it at your stage.
First light
Celestron · 203mm · £2,199
The automated deep-sky platform
- 203mm schmidt-cassegrain on a computerised mount with motorised tracking
- Good for: Moon, planets, bright nebulae, star clusters, and deep-sky objects
- GoTo system finds any object in its database after initial star alignment — no star atlas needed
- Tracking motors keep objects centred as Earth rotates — useful above 100×, essential for photography
- 34kg total — requires a fixed garden spot or car transport
Celestron · 203mm · £1,499
The automated deep-sky platform
- 203mm schmidt-cassegrain on a computerised mount with motorised tracking
- Good for: Moon, planets, bright nebulae, star clusters, and deep-sky objects
- GoTo system finds any object in its database after initial star alignment — no star atlas needed
- Tracking motors keep objects centred as Earth rotates — useful above 100×, essential for photography
- 18kg total — requires a fixed garden spot or car transport
The full picture
The numbers that separate these two scopes — and what they mean at the eyepiece.
Aperture
Equal light-gathering. Aperture won't settle this comparison — the mount, focal ratio, and observing experience are what differ.
Focal length
Same focal length — identical magnification with any given eyepiece. Differences come from optical design and coatings.
Focal ratio
Same focal ratio — the same eyepiece gives equivalent magnification and true field in both scopes.
Mount type
Same mount type — setup experience and ergonomics will be similar. Differences lie in build quality and included accessories.
Weight (OTA)
Celestron CGEM II 8 SCT's optical tube is 5.6kg lighter. Relevant if you plan to use it on multiple mounts or carry the tube to dark-sky sites separately.
Optical design
Both Schmidt-Cassegrain designs — versatile, compact, good for planets and deep-sky. Differences come from aperture and mount.
At the eyepiece
Both scopes · same aperture
Both scopes share essentially the same aperture — views through each will be very similar on all standard targets. The differences show up in setup, mount type, and focal ratio, not in fundamental light-gathering.
The real tradeoff
Both scopes are capable. The question is which one fits the way you actually observe.
The Celestron CGEM II 8 SCT costs 47% more. The premium buys a more capable mount and better build quality, not larger optics. For a first telescope, the Celestron CPC 800 is the smarter entry point. Return to the Celestron CGEM II 8 SCT when you know from experience what you actually need.
The dark side
Every scope has a personality. Here’s where each one gets difficult.
Celestron
Celestron CGEM II 8 SCT
Alignment required every session
GoTo star alignment cannot be skipped — the mount needs to know where it is pointing before it can find objects. This adds several minutes to the start of every session, every time.
Not a spontaneous telescope
At 34kg total, this goes out when you plan to go out — not for a quick look on a clear evening.
Celestron
Celestron CPC 800
Alignment required every session
GoTo star alignment cannot be skipped — the mount needs to know where it is pointing before it can find objects. This adds several minutes to the start of every session, every time.
Not a spontaneous telescope
At 18kg total, this goes out when you plan to go out — not for a quick look on a clear evening.
Which is right for you?
Two different buyers. Two different right answers.
The automated deep-sky platform
Celestron · Celestron CGEM II 8 SCT
You’ll love this if…
- You want to navigate straight to targets without a star atlas — align once and the scope slews to any object in its database on demand
- You observe from a light-polluted garden where star-hopping to faint deep-sky objects would take most of a clear night
- Astrophotography is where you're headed — the tracking equatorial mount is the essential first component of any imaging setup
This will frustrate you if…
- You find the star alignment required at the start of every session frustrating — GoTo alignment cannot be skipped, and several minutes on a cold night before you can observe is the reality
- 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
The automated deep-sky platform
Celestron · Celestron CPC 800
You’ll love this if…
- You want to navigate straight to targets without a star atlas — align once and the scope slews to any object in its database on demand
- You observe from a light-polluted garden where star-hopping to faint deep-sky objects would take most of a clear night
- Astrophotography is where you're headed — the tracking equatorial mount is the essential first component of any imaging setup
This will frustrate you if…
- You find the star alignment required at the start of every session frustrating — GoTo alignment cannot be skipped, and several minutes on a cold night before you can observe is the reality
- 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
At £1,499 versus £2,199, the Celestron CGEM II 8 SCT costs 47% more. The extra money buys a more capable mount and better build quality, not larger optics.
For most buyers starting out, the Celestron CPC 800 is the sensible choice — put the savings into a better eyepiece. The Celestron CGEM II 8 SCT makes sense once you know exactly why you need what it offers. If I had to choose: the Celestron CPC 800, and spend the difference on a quality eyepiece.
Celestron CGEM II 8 SCT
View Celestron CGEM II 8 SCT →Celestron CPC 800
View Celestron CPC 800 →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 | Celestron CGEM II 8 SCT | Celestron CPC 800 |
|---|---|---|
Aperture The most important spec — bigger = more light = better views | 203mm | 203mm |
Focal Length Longer = more magnification potential | 2032mm | 2032mm |
Focal Ratio Lower f-number = wider field of view; higher = more magnification per eyepiece | f/10 | f/10 |
Optical Design The type of optics — each design has different strengths | Schmidt-Cassegrain | Schmidt-Cassegrain |
Coatings Better coatings = more light transmission through the optics | StarBright XLT multi-layer coatings | Starbright XLT coatings |
How do you point it?
| Spec | Celestron CGEM II 8 SCT | Celestron CPC 800 |
|---|---|---|
Mount Type The mechanical system that holds and moves the telescope | GoTo (Computerised) | GoTo (Computerised) |
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 | Celestron CGEM II 8 SCT | Celestron CPC 800 |
|---|---|---|
Focuser Size 2" accepts wider eyepieces and gives better low-power views | 2" | 2" |
Focuser Type Rack-and-pinion is standard; Crayford and dual-speed are smoother | SCT rear-cell focuser with reducer thread | SCT rear-port with 2-inch adapter |
Size & weight
| Spec | Celestron CGEM II 8 SCT | Celestron CPC 800 |
|---|---|---|
OTA Weightⓘ Optical tube only — useful for comparing mount load capacity | 5.4kg | 11kg |
Total Weightⓘ Full setup including mount — this is what you lug to the car | 34kg | 18kg |
Tube Length | 432mm | 432mm |
Tube Material | Aluminium | Aluminium |
What's in the box?
| Spec | Celestron CGEM II 8 SCT | Celestron CPC 800 |
|---|---|---|
Eyepieces Included eyepieces — more is better, but quality matters more than quantity | 40mm eyepiece | 40mm and 13mm eyepieces |
Finder Scope Helps you locate areas of the sky before switching to the main eyepiece | 8x50 right-angle finder scope | StarPointer Pro red dot |
Diagonal Tilts the eyepiece 90° for comfortable viewing — useful on refractors |
Smart features
| Spec | Celestron CGEM II 8 SCT | Celestron CPC 800 |
|---|---|---|
Built-in Camera Records and stacks images automatically — no separate camera needed | ||
App Controlled | ||
WiFi | ||
Battery Included |
Blue highlight: Celestron CGEM II 8 SCT advantage · Amber highlight: Celestron CPC 800 advantage · Greyed cells: equal or subjective.