A ranking you cannot pick a fight with is a ranking you should not rely on. What follows is the whole of how ours is put together, written down so that it can be picked apart.
The rule everything else depends on
Each family is assembled the same way. Read what the maker put in writing. Set it beside the document or the convention that defines the figure. Listen to owners who have had the thing for a year. And then write down, beside every number, where it came from.
That final habit does the heavy lifting. A number with a source behind it can be challenged; a number without one has to be taken on faith. Where a manual and a sales listing disagree, the manual is what appears here. Where neither says anything, the field is left blank and the page states that it is blank — because once a plausible substitute has been set in type, nothing distinguishes it from a real measurement.
Six things a maker publishes, read in a fixed sequence
Anyone buying on this shelf is worrying about three things: whether it will fit what they already own, whether it will show what they are hoping to see, and whether it will still be in use in five years. Six published facts settle those, and they are taken in this order:
- First, the number that decides whether two parts meet at all. The dovetail profile a saddle is cut for, the barrel an eyepiece or a diagonal needs, the thread a filter carries, the back focus a reducer demands, the bayonet a T-ring converts, the outside diameter a solar filter or a dew shield has to close on. It leads because it is the reason most of these products come back, and because no photograph has ever answered it.
- Second, the figure on the front of the box — with whatever gives it meaning attached. Aperture held apart from magnification, which is a division and not a property. A focal ratio shown as the quotient of two published lengths. A payload rating reported as the visual figure the maker actually quoted. A filter named by the band it passes rather than by three letters. An eye relief given as a distance instead of hinted at with the word comfortable. When a maker prints the headline and leaves off the condition, that absence is what gets recorded.
- Third, the small thing that decides whether it is still in service in five years. Whether the eyepiece fitting is a standard barrel or something proprietary. Whether the focuser will hold a camera. Whether a GoTo controller needs an account. Whether the mount can be driven by anything other than its own handset. Every family has one of these, and that is the one written out.
- Fourth, what is not in the box, and what its absence costs. The collimation tool without which a reflector performs like a smaller telescope. The diagonal a refractor needs before it can comfortably point upward. The counterweights a mount ships without. The adapter between one thread family and another. This line carries deliberate weight: anything that needs a second purchase before it works was never the price on the label.
- Fifth, what it costs to go on using. Whether the fittings are made by anyone else. Whether spare parts exist. Whether a coating can be renewed or only replaced. Whether one filter size ties the owner to one supplier. Instruments that lose on the headline number regularly climb above stronger ones on this line alone.
- Sixth, whether it can be bought where you are. Every reference is confirmed store by store, and each page names the markets where an offer was found. Something excellent that nobody stocks in your country is not a recommendation.
Three kinds of source, never given equal weight
For anything structural — apertures, focal lengths, thread and barrel sizes, back focus, the tubes an accessory claims to fit — the manufacturer's own documentation comes first. For anything printed as a headline it comes last, because a headline exists to sell, and on this shelf the headline is very often a magnification.
Second come published ratings and markings: a payload figure, a reflectivity percentage, a transmission at a named wavelength, the standard a solar product cites. These are treated as things to confirm against the current listing rather than as permanent properties, since a maker can change a supplied eyepiece or a coating without changing a model name.
Third, and irreplaceable for one question, come owners a year or two in. No specification sheet says whether a focuser still holds a camera after a winter, whether a plastic thread has stripped, whether an alignment routine is forgiving at four in the morning, or whether anyone still answers the support address. When a judgement rests mostly on one of the three, the page names it. When none of them answers, the page says that too, instead of reasoning its way to a figure.
Positions, not scores
Nothing on this site is marked out of ten. A single figure would have to trade a large Dobsonian against a packet of coloured filters, and there is no honest rate of exchange between them. What appears instead is a place in a family, with the sentence that earned it printed alongside.
Families run upward from the modest rather than downward from the expensive. Almost everyone arrives with a sum in mind and something they want to see; a page that opens on the largest instrument on the shelf is answering a question hardly anybody asked.
The pull this site is built against
Affiliate income leans towards whatever is expensive, recently launched and easy to write about. What resists it here is arrangement rather than good intentions: no family has ever been reordered because of what something earns, several pages finish by recommending a collimation tool or a chair instead of a larger tube, and no position has ever been exchanged for anything whatever.
There is one distortion peculiar to this subject, and saying it out loud works better than quietly resisting it. Telescopes are sold on magnification. Build a page around the biggest number and it finishes by recommending whichever instrument claims the most power, without mentioning that the claim comes from supplying a poor eyepiece, that the aperture cannot support it, and that the atmosphere would refuse it on most nights anyway. Nothing here is built that way. Where the honest answer is that an upgrade changes nothing — a wider field behind a focuser that will not accept a two-inch barrel, a heavier tube on a mount already at its limit, another filter for a galaxy that shines right across the spectrum — that is the answer the page gives.
One bias cannot be arranged away: what is covered here is what can actually be bought through the Amazon stores of the United States, the United Kingdom, Germany, France, Italy and Spain. Equipment sold only direct by its maker, or through specialist dealers, is under-represented as a result, and where that shapes a recommendation the page says so.
Numbers are quoted, never worked out here
This subject is sold on figures, and a figure is the easiest thing in a listing to repeat without thinking about it. One rule covers every page carrying one: every aperture, focal length, focal ratio, secondary obstruction, payload rating, apparent field, eye relief, exit pupil, reflectivity, transmission percentage, back focus, barrel and thread size, weight and quoted temperature on this site is copied from the manufacturer, in the unit it was published in, with its source named — and not one of them is recalculated, converted or inferred by us. When a maker publishes nothing, the page says nothing has been published rather than offering a substitute.
Magnification is where that rule earns its place, because it is the one figure that cannot belong to a product at all. It is a quotient. It changes with every eyepiece. A listing that prints one has chosen an eyepiece on your behalf. So this site prints the two focal lengths and leaves the division where it belongs. Nor is any instrument here called sharper, brighter or more capable than another on the strength of a specification sheet alone.
What a published figure is actually promising
One idea underlies all of the above, and it is why these pages read more flatly than the ones next to them in a search result: a published figure describes a piece of equipment; it does not undertake to deliver a result. An aperture says how much light the optics can gather, not how much a given night will let through — the atmosphere sets a ceiling on most evenings that no purchase lifts. A payload rating says what a mount will hold while somebody looks through it, not what it will guide for ten minutes with a camera hanging off the back. A transmission curve was measured in a laboratory and undertakes nothing about a suburban sky. Treat any of them as a promise and you sell more equipment, at the cost of disappointing somebody with a product that did exactly what its sheet said.
The two sentences this site refuses to write
Two limits are fixed here, and both are better said than left to be worked out. Nothing on this site — no filter, no pair of eclipse glasses, no mounting arrangement — is described as making an observation safe. A page reports what the maker specifies for its own product: the standard a listing cites, the construction, the fitting, the inspection asked for before use. The rest belongs to those instructions, because whether an observation is safe depends on the state of the filter, the way it is fitted and the person fitting it, and no listing knows any of that. And aperture and magnification are never allowed to blur into each other: one is what the optics collect, the other is how thinly that light is spread, and a ranking built on a mixture of the two would be comparing things that cannot be compared.
The point at which a page stops
None of this stands in for the manufacturer's instructions. For anything aimed at the Sun, for a filter that has to be inspected before it is fitted, for eclipse glasses and how they are kept, and for a mount carrying a load near its rating, the page points at those instructions instead of rewording them — even though a page that stops there earns nothing.
And one limit is restated wherever it applies rather than assumed once: whether two things fit is settled by a number or a list the maker published, and never by how they look. The dovetail profile decides which tube a saddle will hold. The barrel decides which eyepiece enters a focuser. The thread decides which filter screws in. The back focus decides whether a reducer reaches focus at all. The outside diameter of a tube — not the aperture of its optics — decides which solar filter closes on it. Where a maker publishes none of that, the page reports that the answer is unpublished rather than deducing it from a photograph or a product name.
The questions that keep arriving
Is there any way to pay for a place in a ranking here?
There is not. No fee, no loaned instrument and no arrangement of any kind has ever decided where something sits. If that ever changed, the page concerned would carry the fact in its own text, where it would be read, and not in a line at the bottom of the site.
Where do the figures on these pages come from?
From what manufacturers publish — specification sheets, manuals, compatibility lists — from the documents and conventions that define those figures, and from what owners consistently report after a year or two. Each page says which of the three a given judgement leans on, so an aperture or a payload rating appears as something somebody wrote down, not as a promise about your own sky.
How can a cheaper instrument end up above a dearer one?
Because the order follows what the instrument has to do. A modest telescope on a mount that settles in a second shows more, on more evenings, than a larger one that trembles for four — and someone who can aim it will take it outside twice as often.
Does anything here ever conclude that you should buy nothing?
Regularly. Collimating the tube, carrying it outside an hour earlier, sitting down at the eyepiece and waiting for a steadier night each do more than most purchases, and the pages that say so earn nothing at all.
Why will you not reprint the magnification from the box?
Because no telescope has one. Magnification is the tube focal length divided by the eyepiece focal length, so it changes with every eyepiece and grows as the supplied eyepiece gets worse. We publish both focal lengths and the aperture, which is what decides whether there is anything worth spreading out.
Last reviewed 17 September 2026