About thermalranker
The detection range printed on a thermal scope’s box is usually the distance at which a standing person spans about two pixels — a warm smudge you could not tell from a fence post. thermalranker takes two numbers the same manufacturer publishes, pixel pitch and lens focal length, and works out the much shorter distance at which that smudge becomes a person, a hog or a coyote. Both figures sit side by side on all 67 unit pages, each one labelled for what it is.
The number the spec sheet does not print
Divide pixel pitch in micrometres by focal length in millimetres and you have the angle one pixel sees, in milliradians. From there the Johnson criteria say how many pixels across a target’s critical dimension an observer needs: about 2 to know something is there, 8 to say what kind of thing it is, 13 to say which one. Against the 0.5 m width of a standing human that arithmetic produces three ranges instead of one, and the middle one — recognition — is the only one worth planning a hunt around.
This is not an accusation of dishonesty. A maker measuring against a person’s 1.8 m height at two pixels is answering a different question, and across the catalog the box figure runs from 1.4× to 5.1× the estimate depending on which yardstick the maker picked. Both appear on the page; neither is hidden behind the other. The full working, including why the model ignores weather and the eyepiece, is in how we compare.
How units are classified, and where specs come from
67 units are sorted into 4 types — riflescope, handheld monocular, clip-on, binocular — then cross-cut by 8 sensor classes, named by pixel width the way the market names them (“a 640” is a 640×512 or a 640×480 core, and nobody shops by the second number), and by 9 objective focal lengths, because focal length is the other half of every range figure here.
Every one of the 67 entries carries a named source: the maker’s own product page or datasheet, read and recorded, and printed on the unit’s page so the figure can be checked against it. Where two published sources disagreed, the manufacturer’s own number won. Where a unit’s published field of view disagrees with the one its sensor and lens imply by more than 15 % — 1 of 65 units here — both numbers are shown and the gap is flagged, rather than quietly reconciled into whichever one looks better.
What is left blank
A missing figure stays missing. 16 of 67 units publish no NETD, the sensor’s thermal sensitivity in millikelvin, so those cells are empty rather than filled with a plausible number for that sensor class. 11 publish no ingress rating, which is not the same as being unsealed and is not written up as though it were. 45 do not say where the unit is assembled. 7 publish no detection claim at all, so those pages show the estimate standing on its own with nothing to compare it against.
Owner sentiment, and why there is none yet
Public owner discussion is worth reading and will be summarised here when it has actually been read — in its own section, labelled as owner experience rather than blended into a spec table, and dated. Until then this site publishes none, because “owners report” written about devices whose owners nobody has read is fiction dressed as research.
Star ratings work the same way. Every unit has somewhere to hold one; 0 of the 67 hold one, because the code refuses any rating without a cited source and will not reprint a retailer’s stars. A thermal scope with no rating on this site is a scope whose rating has not been earned honestly yet.
The range arithmetic has nothing to gain
Two people, around other work. No office, no test lab, no staff; nobody here has carried all 67 of these units into a dark field, and the site never claims otherwise. What it adds is one piece of arithmetic applied identically to every maker’s own published numbers, written in a single file, so a range figure can only be wrong in one place and is wrong for everybody at once when it is.
No manufacturer, importer or dealer pays to be listed, to rank higher, or to be written about, and none sees a page before it publishes. The site carries no retailer links and no affiliate links of any kind, so no ordering here can earn anyone a commission. Prices exist only as an approximate snapshot with a band attached, because thermal pricing moves on closeouts. What is collected from visitors, and what is not, is set out in the privacy policy.
How often the data changes
The catalog was last read and recorded on 2026-09-20, and that date — not the day the page was rendered — is what every timestamp on the site reports. It moves when a maker revises a datasheet, when a new core or lens combination ships, or when a listed price has drifted far enough that the band is wrong. A specification found to be wrong is corrected and the source note is updated with it; a correction sent in is the fastest way that happens.