Digital night vision

What it means

Digital night vision uses an electronic image sensor, the same kind found in cameras, tuned to be very sensitive in low light. The sensor also picks up near-infrared light, just beyond what the eye can see. The picture is shown on a small screen in the eyepiece. Most units carry an IR illuminator, a flashlight of infrared light, because on a dark night there is not enough natural light for the sensor alone.

What it changes in the field

Digital night vision shows the scene as reflected light: you see eyes shining, fence posts, the texture of brush and the markings on an animal. That makes it good for confirming what you are looking at once you know where to look. It does not see heat, so a coyote lying still in tall grass can be invisible to it while plain on a thermal.

Most units show full color in daylight, so one device can work day and night. They cost less than tube night vision and are not harmed by bright light, though muzzle flash and headlights can briefly flare the screen.

How it compares

• Against thermal: thermal finds animals; digital helps identify them, and it can see an infrared laser that thermal cannot.
• Against tubes: good tubes see more in starlight without an illuminator and have no screen lag. Digital is cheaper, records easily and works by day.

What to look for

• The illuminator: wavelength, and whether it is built in, included or optional.
• How the maker measured its detection range: with IR on, in daylight, or not stated.
• Display resolution against sensor resolution. A high-resolution sensor on a small screen needs zoom to show its detail.

How we use it on this site

The pixel math works for digital units, from field of view divided by sensor width. Where we show it, it is a detail limit in good light. At night, sensor noise and the illuminator’s reach usually limit you first, and no maker publishes enough to calculate that.