Reflector telescopes
A finished telescope, or the mirrors to build one?
These sit on the same shelf and are not the same kind of purchase. One arrives as a telescope with a mount, a tripod, eyepieces and an app that steers the observer to a target; the other is a primary and a secondary mirror, with the tube, focuser and mount to be found elsewhere.
| Compared on | StarSense Explorer DX 130 (22461) | D150F750JP |
|---|---|---|
| Aperture | 130 mm (from the title and bullets) | 150 mm (maker’s bullet) |
| Focal length | The listing does not carry it | 750 mm (maker’s bullet) |
| Optical design | Newtonian reflector, high-reflectivity coating per the maker | Not published by the maker. |
| Mirror coating | Not published by the maker. | 1/10 λ surface accuracy and 92 per cent over 400–950 nm, as the maker states them; enhanced aluminium with a protective layer |
| Secondary obstruction | Not published by the maker. | Major axis 50 mm, minor axis 35 mm |
| Collimation access | Not published by the maker. | Not published by the maker. |
| Mount supplied | Manual alt-azimuth with dual-axis slow motion and a sliding rod | Not published by the maker. |
| Supplied accessories | StarSense dock and app, 25 mm and 10 mm eyepieces, erect-image diagonal, red dot finder, full-height tripod | Mirror set for a Newtonian: primary and secondary, not a complete telescope |
A tick means one listing published something the other did not, or published a better figure. It does not mean the product is better, and the column is not a score out of anything: a maker who says less loses lines here without losing a comparison. The two verdicts below are where the page is settled.
A telescope, finished. Everything needed for the first night is in the box, and the phone dock answers the question that stops most beginners — where is it. What the listing never gives is a focal length, so no eyepiece magnification can be worked out from it.
Two mirrors, and the best-published optics on this shelf. One-tenth wave of surface accuracy, ninety-two per cent reflectivity across a named band, and both axes of the secondary — figures that no complete telescope here publishes. It is not a telescope: the tube, the focuser, the mount and the tripod are all still to be found.
It describes how closely the mirror matches its intended shape, measured in fractions of a wavelength of light. Smaller fractions mean a more accurate surface; it is a figure almost never published on a complete telescope.
No. A Newtonian needs a tube of the right length, a focuser, a spider to hold the secondary, a cell for the primary and a mount. The mirrors are the optics only.
The secondary blocks part of the incoming light and slightly reduces contrast. Publishing both axes lets that fraction be worked out, which is why serious mirror listings give it and complete-telescope listings usually do not.
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
150 mm mirror · 750 mm focal length · optics only
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.
Best for: Somebody rebuilding or building a Newtonian around a known mirror set
≈ £99 / €99
Any figure written into the body of this page was true on the day it was written. The amount shown next to each instrument is requested from the retailer as the page loads, and it is that amount, not the text, that stands.
