This is a critical question for hunters who don’t want to spook game.

Near-IR (850nm and 940nm): The illuminators used in most consumer night vision and trail cameras operate in the near-infrared range. The scientific evidence on animal perception of near-IR is mixed, but practical experience from hunters strongly suggests that deer and other cervids can detect 850nm IR illumination — the faint red glow is within the range of their visual system. This is why 940nm “no-glow” illuminators are preferred for hunting applications.

At 940nm: Most mammals cannot perceive 940nm illumination. This is considered the “invisible” IR band for hunting and stealth applications.

Thermal IR (8–14 microns): Completely invisible to all mammals.

For any hunting application, use 940nm illuminators or devices operating at 940nm to avoid alerting game. If using a device with an 850nm emitter, minimize IR output (use lower power settings) and observe animal behavior for signs of detection.