Security camera night vision: infrared vs color

How infrared night vision works

Most security cameras with night vision carry a ring of infrared LEDs around the lens. At night, a filter in front of the sensor moves out of the way, and the LEDs light the scene with near-infrared light that people cannot see but the camera can. The result is a monochrome image. Reference sources describe active infrared systems as using illumination in the 700 to 1,000 nanometer range and producing a monochrome image on a normal display, which matches what you see on a camera feed. These systems are commonly found in residential security.

Two practical points follow. IR range depends on the number and power of LEDs and on what the light bounces off: a wall, a car and a tree return light well, while an open yard returns almost none. And IR cannot show color, so a red jacket and a gray jacket look similar, which matters when you want to describe a visitor.

How color night vision works

“Color night vision” is a marketing label for a family of approaches. Some cameras use a large lens aperture and a sensitive sensor to gather ambient light and still show color. Others add a warm white spotlight that switches on at night or when motion is detected. In both cases the camera needs some visible light. With enough light, you get color footage; with too little, the picture gets grainy or the camera falls back to infrared.

• Sensitive-sensor models work with a porch light, a streetlamp or a bright moon. They need no spotlight but are limited by the light available.
• Spotlight models light the scene themselves. They give the fullest color, but the light is visible: it can deter someone and also annoys a neighbor when it switches on for a passing car.
• Hybrid models offer a choice in the app: infrared all night, color when motion is detected or color all night.

Infrared vs color at a glance

Why infrared fails behind glass

If you mount an IR camera inside a window, the LEDs light up the pane itself. Light reflects back into the lens, and the picture is a bright haze with the outdoors barely visible. Room lights and screens can also reflect in the glass. To fix this, turn off the camera’s infrared and rely on a porch light, move the camera outside under an eave or press the lens against the glass with the LEDs blocked, if the manufacturer allows it. This is also why a video doorbell on a glass storm door has trouble at night.

Reflections, insects and rain

• Close surfaces bounce IR. A camera mounted near a wall, a pillar or a soffit can flood the image with its own light. Mount the lens a few inches clear of the surface behind it.
• Insects and rain at night light up in IR and look like streaks or orbs. A sheltered position under an eave reduces this, and so does turning off the IR ring when you rely on another light.
• Spider webs across the lens glow and trigger false alerts. Brush them away.

The light often matters more than the camera

A good outdoor light improves almost any camera at night. Motion-activated fixtures save energy and give a color camera the light it needs; ENERGY STAR notes that certified outdoor fixtures offer features such as automatic daylight shut-off and motion sensors. Aim lights so they do not shine into the lens or into a neighbor’s windows, and see outdoor smart lighting for options. Facing away from a lit street or a bright window also helps; see where to place security cameras for angles.

What to look for when you buy

• Stated night range in feet, and whether it is for infrared, color or both. Treat the figure as a maximum in ideal conditions.
• An option to choose infrared, color or auto in the app.
• A sensor and lens described as low-light capable; a larger aperture helps color in dim conditions.
• Resolution of 2 MP or more so faces survive digital zoom.
• An adjustable spotlight, with brightness and a way to switch it off, if you do not want light at 3 a.m.

Your video doorbell has the same trade-offs, but its range is shorter; see where and how high to mount a video doorbell.