What Does "IR Range" Actually Mean?
An advertised "night vision range" or "IR range" (e.g. "100 ft") states the distance at which a manufacturer's infrared illuminator produces a usable image — but "usable" is rarely defined, and when implied, it typically means you can tell something is there (the Detect criterion under the DORI standard), not that you can recognize who or what it is.
The one thing to know: An advertised IR range (e.g. '100 ft night vision') is almost always measured to the criterion of 'barely detectable' — you can tell something moved — not 'identifiable,' where you can make out a face. Manufacturers rarely state which criterion they used, so two cameras both claiming '100 ft' can have wildly different real-world usefulness for actually recognizing who is in frame. Under the EN 62676-4 DORI standard, Identification requires roughly 10x the pixel density of Detection at the same distance — so 'detect at 100 ft' does not remotely imply 'identify at 100 ft.'
Why identical range claims don't mean identical performance
IR range depends on more than the illuminator's rated output: sensor sensitivity (minimum lux), lens aperture, the reflectivity of the scene being illuminated, and the measurement criterion used. None of these variables are standardized across the industry the way, say, camera resolution is. Two cameras claiming "100 ft" can differ meaningfully in what you can actually make out at that distance.
Scene reflectivity changes real-world range
Infrared illuminators are defeated by glass and reflective surfaces in ways visible light is not: shooting through a window typically reflects the camera's own IR back at the lens, washing out or blinding the image (the same reason phone cameras struggle through car windshields at night). IR range is also highly scene-dependent — a dark, non-reflective backyard absorbs far more IR than a light-colored wall or driveway, so the same camera's real-world range varies by scene, not just distance.
What to look for instead
Prefer a camera that discloses aperture (f-stop) and minimum illumination in lux over one that only advertises a distance in feet with no supporting specs — see the Night Vision Reality Index for which cameras disclose what. And use the DORI Pixel-Density Decoder to estimate whether a given resolution and distance combination can reach Identification-level detail at all.
This page is general reference information about how IR range claims are typically measured, not a specification of any single product's real-world performance.
Frequently Asked Questions
It's the manufacturer's claimed distance at which the infrared illuminator produces a usable image — but 'usable' is rarely defined, and when it is, it's typically the Detection criterion (something is visibly there), not Identification (you can recognize who it is). The same '100 ft' claim from two brands can mean very different real-world usefulness.
Because IR range depends on more than the illuminator's rated distance: sensor sensitivity (minimum lux), lens aperture, scene reflectivity (a light-colored wall reflects IR much better than a dark, non-reflective yard), and whether the manufacturer measured range to a reflective test target versus a realistic outdoor scene. None of these variables are standardized across brands.
Poorly. Infrared light reflects off glass back toward the camera's own lens, typically creating a bright glare or hotspot that washes out the image rather than illuminating the scene beyond the glass. This is a physical limitation of IR illumination, not a specific camera defect.
Not necessarily — a longer claimed range with an undisclosed measurement criterion tells you less than a shorter range from a manufacturer that discloses minimum illumination in lux and aperture. We'd trust a camera with disclosed lux/aperture specs and a modest range claim over an undisclosed 150 ft claim with no supporting specs.