Who writes this

Jean-Benoit Buisson

Every page on SkyVerdict is written and signed by one named person. This page explains where the judgments come from, lists what the author is not, and gives an address for corrections.

What set this off

It started with a magnification. A telescope sold on a figure in the hundreds, printed in the largest type on the box. A telescope does not have a magnification. It is a quotient — the focal length of the tube divided by the focal length of whichever eyepiece is fitted — so the figure on the packaging is really a statement about a supplied eyepiece, and supplying a poorer one makes it larger. What decides what can be seen is the aperture, which is printed smaller or not at all. Once that gap is visible, the same pattern turns up across the whole shelf. A mount sold on a payload rating quoted for observing and read as though it were a photographic one. A filter sold under a three-letter name that says nothing about the band it passes. A finder sold without the bracket that fits it. And most pages that answer the question look alike: a ranked list, a score, a button, and no figure a reader could check against the maker's own sheet.

The second problem arrives after the box is open. These instruments are bought on a headline and kept or returned on details. A telescope whose focuser will not take a two-inch barrel, so the wide-field eyepiece bought for it cannot go in. A reducer whose back focus cannot be reached once the camera and the filter wheel are counted. A solar filter ordered on the aperture of the optics rather than the outside diameter of the tube. A mount whose saddle is cut for a narrow dovetail and a tube that carries a wide one. A tripod that damps for four seconds. None of it is printed on the front of the packaging, and each one decides whether the purchase works.

So the site does the dull part. It reads what manufacturers publish, checks each product against its Amazon.com listing, and writes down the line that settles the question — the aperture next to the focal length rather than a magnification, a payload rating next to the use the maker quoted it for, a filter's band rather than its initials, the outside diameter a cell has to close on — and it says so plainly when a figure is not published at all. That last habit matters more than it sounds: much of the disappointment on this shelf comes from a number nobody printed, or from one printed without the condition that gives it meaning.

Behind the pages are notes: the specification that matters for each family, the places where a manual and a sales page disagree, which barrel, thread and dovetail standards an instrument ties its owner to, what a maker means when it prints a payload figure, and the buying mistake each family invites. The site is those notes put in order, in five languages, because the same questions are asked in French, German, Spanish and Italian and are answered worse in most of them.

What has been written up to date

This list writes itself out of the catalog, a link for every page that has gone up, so it changes whenever a family opens or a reference is withdrawn. It records what has been written about — and not, to be clear, what sits in anybody’s closet.

Three things I am fairly sure of

The figure printed largest is hardly ever the figure that settles anything. A telescope is sold on a magnification when the aperture is what limits it; a mount on a payload figure when the stiffness of its tripod is what limits it; an eyepiece on an apparent field when the eye relief is what decides whether it can be used at all; a filter on a name when its bandpass is what decides whether it does anything for the object being looked at. What an instrument costs to keep outlives what it cost to buy. A proprietary eyepiece fitting ties every later purchase to one maker; a plastic focuser decides what can ever hang off the back; a controller that insists on an account determines what a mount is worth in its third year; a tube left uncollimated performs like a smaller one for years. And what finally decides a purchase is very often nowhere on the specification sheet: how long the image takes to stop trembling, whether the finder bracket fits anything else, and whether a part will still be sold when the first one gives out.

What I am not

I am not an optician, an astronomer, an optical engineer or a telescope maker. I hold no qualification in those fields, I have never worked for a manufacturer or a retailer, and nothing on this site rests on a professional title. A page here describes a product — its dimensions, its stated figures, its published specifications — and stops there. In particular, 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 and weight on this site is reported from the manufacturer, with its unit as published and its source named, and never derived by me. When a maker gives a figure under a named condition, the page attributes both to the maker and keeps them together, and nothing here is described as sharper, brighter or safer than something else because a specification sheet says so.

This site is not an operating manual and not safety advice. For anything pointed at the Sun, for a filter that has to be inspected before every use, for eclipse glasses and how they are stored, and for a mount asked to carry a load near its rating, it points to the maker's instructions, the markings on the product and the standard the listing cites, rather than paraphrasing them. Two statements are repeated rather than assumed. Aperture and magnification are different quantities and stay apart, and each page says which of the two its maker actually published. And no filter, no pair of eclipse glasses and no mounting arrangement is described here as making an observation safe: a page reports what the maker supplies and what the marking states, and the rest belongs to the maker’s instructions.

None of this is meant to be taken on the strength of a byline. Whatever a judgment leans on is written into the page that makes it, and how a family gets its order is set out at greater length elsewhere.

The working rules

No figure appears without saying where it came from — a datasheet, a manual, a marking, a named standard, or what owners keep reporting after a year with the thing.
Nothing gets made up: not a price, not a reference, not a specification. Where a maker has published nothing, the row stays empty and the page says so in words.
Each reference is checked against its Amazon.com listing before its page is published. Where a model has no offer in that store, the button searches your own store instead of opening a listing that has gone.
Where the less expensive option is the right one, the page says so — and where the real answer is to collimate the tube, carry it outside an hour earlier or sit down at the eyepiece rather than buy anything, it says that instead.
No page is organized around a headline number. Nothing is ordered by the largest magnification printed on a box, and where a new model is barely distinguishable from the last one, the page says so.

What a misread figure costs on this shelf

Because this equipment is sold on figures that describe something other than what the buyer needs, to people who will then spend cold evenings working out why. A magnification appears where an aperture belongs. A visual payload rating appears where a photographic one belongs. An apparent field appears where an eye relief decides whether the eyepiece can be used at all. And the parts everyone treats as extras — the collimator, the diagonal, the counterweight, the chair, the bracket that genuinely fits the finder — frequently decide whether any of it works.

Quite a lot of what is worth knowing here is free. If one sentence has to carry the rest, it is this: a published figure describes a piece of equipment, and undertakes nothing about a result. Much of what makes an instrument perform better is free: collimating it, carrying it outside an hour before using it, sitting down instead of standing, letting the eyes adapt for twenty minutes without a white light, and waiting for a steadier night rather than blaming the optics for the atmosphere. Sites that exist to shift hardware pass over those steps. They are not passed over here.

Corrections

If something here is wrong, say so and it will be put right, with the date of the correction left on the page. Write to [email protected].

Jean-Benoit Buisson · SkyVerdict · Paris, France