Instrument class
250–300 mm Dobsonian
Where galaxies start having structure and planetary nebulae start having colour. Also where an instrument starts needing a plan rather than a decision.
| Aperture | 250–300 mm |
|---|---|
| Focal ratio | f/4.7–f/5.5 |
| Typical weight | 40 kg |
| Setup time | 15 minutes |
| Learning curve | 3 out of 5 |
| Price band | €800–2000 |
| Useful magnification | 46× to 550× at 275 mm |
What it does well
- Spiral structure in the brighter galaxies, from a dark site
- Enough light that a nebula filter finally has something to work with
- Still the cheapest route to this much aperture by a wide margin
What it costs you
- 40 kg in two or three pieces. It needs a car, a plan and a body that agrees
- A cooling-down period of half an hour or more before it performs
- Under a bright sky, most of this aperture is buying background glow
Fit against each goal
Nebulae, clusters and galaxies, by eye · 5 out of 5
The reason people own these. Nothing else at the price shows as much.
The Moon and the planets · 4 out of 5
Superb when the seeing allows, which is less often than the aperture would like.
Learn my way around the sky · 2 out of 5
Not the instrument to learn on. The field is narrow and the setup is a commitment.
Taking it with me · 1 out of 5
No.
Models in this class
Indicative European street prices with the date they were observed. Ordered by price. Links marked paid link earn us a commission and cost you nothing extra.
Sky-Watcher Skyliner 250PX
€950seen 2026-08-17254 mm · 1200 mm focal length · f/4.7 · 38 kg
With a 10 mm eyepiece: 120×, 2.1 mm exit pupil.
Mount Full-size Dobsonian rocker box
The tube alone is 20 kg and awkward rather than heavy. Measure your car boot before ordering.
Where to buy
- Amazon.frships FR
- Astroshopships DE, FR, EU
- First Light Opticsships GB
- Optique Unterlindenships FR
- Pierro Astroships FR
- Teleskop-Expressships DE, EU
None of these links earn us anything.