The most aperture per euro, and an alignment to keep · review
A 150/750 Newtonian mirror set — primary and secondary — sold on its own, with published surface accuracy and reflectivity figures rather than as a complete telescope.
The bottom line An optical set with unusually specific published figures, aimed at a builder rather than at a buyer looking for a telescope.
A primary and a secondary for a 150 mm f/5 Newtonian. No tube, no cell, no spider, no focuser, no mount, no eyepiece. The listing is clear about this, and it is the first thing a reader needs to know, because every other product on this shelf arrives ready to point at something.
Surface accuracy given as 1/10 λ. Reflectivity given as 92 %, with the waveband it applies to — 400 to 950 nm — written next to it. Coating described as enhanced aluminium with a protective layer. Secondary axes given as 50 mm and 35 mm. That is more numerical detail than most complete telescopes publish, and every one of those figures is the manufacturer’s.
Somebody re-mirroring an old tube, or building one. The 50 mm minor axis of the secondary sets the fully illuminated field, and the f/5 ratio sets how much the rest of the build has to get right — spider, cell, and a focuser square to the axis.
Whether the mirror meets its published figure. That is a bench measurement, and it belongs to whoever performs it; this page reports what the maker states and stops there.
German, French, Italian and Spanish Amazon stores sat at about 99 € on the day of the survey.
British Amazon store lists it in local currency, which the euro range above sets aside.
American Amazon catalogue holds a record for it that nobody is selling.
Figures as Keepa reported them on the day this page was last updated. Stock and pricing shift without warning.
Prices quoted in this text were read on 17 September 2026. The live price is at the top of the page.
| Aperture | 150 mm (maker’s bullet) |
|---|---|
| Focal length and ratio | 750 mm (maker’s bullet) · f/5, the quotient of the two figures above |
| Optical design | Not published by the maker. |
| Mirror coating | 1/10 λ, as the maker states it · 92 % over 400–950 nm, as the maker states it · Enhanced aluminium with a protective layer |
| Secondary obstruction | Major axis 50 mm, minor axis 35 mm |
| Focuser type | Not published by the maker. |
| Tube length | Not published by the maker. |
| Collimation access | Not published by the maker. |
| Mount supplied | Not published by the maker. |
| Supplied accessories | Mirror set for a Newtonian: primary and secondary, not a complete telescope |
| Amazon reference | B0B5RQJGFS (same reference on 6 Amazon marketplaces) |
| EAN | 0741754671244 |
No. It is the optical set — primary and secondary — for a 150 mm f/5 Newtonian. The tube, spider, mirror cell, focuser, finder and mount are all separate.
It is a statement about how closely the mirror surface follows its intended shape, expressed as a fraction of a wavelength. It is the maker’s published figure; this page reports it and does not verify it.
114 mm aperture · 500 mm focal length
A 114/500 Newtonian on an equatorial mount, supplied with two eyepieces, a 3x Barlow, an LED red dot finder and a smartphone camera adapter.
Best for: Wide, bright views of extended objects rather than high-power planetary work
≈ €199
130 mm aperture · smartphone sky recognition
A 130 mm Newtonian on a manual alt-azimuth mount whose dock and app read the star field through the phone camera and steer the observer to a target with on-screen arrows.
Best for: A beginner who wants to see things this month rather than learn to star-hop first
≈ $500 / £399 / €436
114 mm aperture · 1000 mm focal length
A 114/1000 Newtonian on an EQ-1 equatorial mount, supplied with four eyepieces, a 2x Barlow, a 5x24 finder and a Moon filter.
Best for: Lunar and planetary observing on a budget, with eyepieces already covered
≈ €259
