Night vision security cameras for NYC buildings and construction sites
How a camera sees after dark, which light gives you color and which gives you black and white, why a camera's own infrared ruins its picture, and how to cover a construction lot from a temporary pole, worked through with the numbers.
Technical figures checked against the sources listed at the end.
A night vision security camera sees in the dark in one of two ways: it lights the scene with its own infrared LEDs and records in black and white, or it uses visible light that is already there, from a streetlight, a fixture over the door or a white light on the camera, and records in color. Which one you get depends on how much light reaches the person compared with the camera's rated minimum illumination: on a lit NYC street a low light camera can stay in color, while a dark rear yard or a construction lot needs infrared or added light. Most bad night video comes from the camera's own infrared bouncing back off something close to the lens, such as an eave, a wall, rain or a spider web.
So the longest infrared range on a spec sheet is the wrong place to start. The questions that decide a night camera are where the light at each spot comes from, what the camera needs in order to use it, and what sits within a few feet of the lens. Each is worked through below, with figures that compute the answer.
The figures use one example: a four-story mixed-use building in Queens with a shop on the ground floor, a front door under a shallow canopy, a dark rear yard behind it, and the lot next door, where a new building is going up behind a plywood fence. It is an example, not a client's building.
01How night vision security cameras work
By day a camera looks through an infrared cut filter, a thin piece of filter glass that blocks infrared so colors come out right. When the light falls below a level set in the camera, a day and night camera slides that filter out of the way, switches the picture to black and white and turns on the infrared LEDs around its lens. Most of those LEDs emit at about 850 nanometers, just past the red people can see. Look straight at them at night and you see a faint red glow.
The switch to black and white is not a cost cutting choice. With the filter out, infrared reaches every color channel of the sensor at once and the colors it would show are wrong, so the honest picture is gray. It is also a different picture. Under infrared, things show by how much infrared they reflect, not by their color: many dyes reflect infrared well, so a red or navy jacket can come out pale gray, skin comes out light, and two cars of different colors can look the same.
The other way to see at night is to need less light. A low light camera, often sold under names such as starlight or full color, keeps the cut filter in and records color in very little light, using a wide aperture lens and a sensor with larger pixels. It still needs some visible light. When there is not enough, it either switches to infrared like any other camera or turns on a white light of its own.
What the datasheet tells you
Look for the line called minimum illumination. On the example standard camera it reads "Color: 0.005 lux (F1.6, AGC on)" and "0 lux with IR on". The first number is the dimmest light, falling on the scene, at which the maker still got a color picture with the gain turned all the way up. The second says only that the camera brings its own light. A lux is one lumen per square meter: the light falling on a surface, not the light a lamp puts out.
Infrared LEDs at 940 nanometers show no glow at all, which some owners want. The trade is reach. Camera sensors are less sensitive that far into the infrared, and one maker puts 940 nanometer illuminators at about 30 to 40 percent less effective, so they light a shorter distance. Most security cameras use 850.
02Color night vision vs infrared: which light gives you color
Night light is small numbers. A clear sky with no moon puts about 0.002 lux on the ground, a full moon on a clear night 0.05 to 0.3 lux, and an overcast sky with no moon about 0.0001. Those are natural sky values; the glow of a city sky adds to them, by an amount that changes with the clouds. Streetlights are a different scale. The roadway lighting practice that U.S. road agencies design to, IES RP-8, sets a minimum of 0.1 footcandle, about 1.1 lux, on a vertical surface at face height for a residential street, and 1.0 footcandle, about 11 lux, for a busy commercial street.
Figure 1 adds up the light at the example building's front door and holds it against two real camera ratings. Pick the street, the sky and the door light, then the camera.
street 0 + sky 0.002 = 0.002 lux
A rear yard, a side passage or a dark lot that no streetlight reaches.
Light ÷ rating: 0.002 ÷ 0.005 = 0.4
Black and white, on infrared
The light at the door is below the rating, 0.4 times what the camera needs for color, so it drops its filter and lights the scene with its own infrared. Shapes and movement, no colors: the red jacket shows as light gray, because many dyes reflect infrared.
Two things stand out. On any street lit to the IES targets, both cameras have hundreds or thousands of times the light they need, so a camera that drops into black and white on a lit sidewalk is usually doing it because of its day and night setting, not because the light ran out. And in a rear yard with no streetlight, the low light camera holds color on a clear night with no moon while the standard camera has to fall back to infrared. Cloud over the city cuts the natural sky light further; turn the sky to overcast and both cameras run out.
Reading a minimum illumination rating
Light reaching the sensor goes with one over the F-number squared. The example low light camera has an F1.0 lens and the standard camera an F1.6 lens, so the wider lens passes (1.6 ÷ 1.0)² = 2.56 times as much light. Their ratings differ by 0.005 ÷ 0.0003, about 17 times. The lens explains part of that; the larger 1/1.8 inch sensor, against the standard camera's 1/2.7 inch, and the maker's test explain the rest.
That last part is the catch. Makers do not all test the same way: how bright the picture must be, how slow the shutter, how much gain. Treat a rating as a best case, compare two ratings only at the same F-number, and be wary of comparing two makers' numbers at all. A night look at the actual spot settles it.
Slow shutters, grain and storage
To find more light, a camera can hold its shutter open longer, which blurs a person who is walking, and turn up the gain, which fills the picture with grain. Grain is detail to the video encoder, so a noisy night picture often needs more bitrate than the same scene by day. Size the recorder for the night picture, not the day one; our guide to how long security camera recordings last shows the storage math.
Cameras with a white light
Some low light cameras carry a white or warm LED that comes on at night, either all night or when the camera detects a person. They give you color where there is no other light. The light is visible to everyone, including the neighbors: aim it at your own door or yard, not at windows across the street, and look at it from the street at night before you leave it on.
NYC streetlights are LED now
NYC DOT has retrofitted almost all of the city's streetlights with LEDs. White LED light covers the visible range, so a color camera under a streetlight records real colors, which the orange sodium lamps they replaced made hard to tell apart. What a streetlight does not do is light a doorway evenly. The pool under the pole is bright; a door recessed three steps back, or shadowed by a canopy, can get a small fraction of it. Judge the light where the person will stand, at face height, not at the curb.
03How far night vision reaches, and what the IR range means
The infrared range on a datasheet, up to 30 m (98 ft) for the example standard camera, is how far the camera's own light reaches with usable brightness by the maker's test. It is not how far you can identify someone. The light spreads as it travels, so a person at half the rated range gets 4 times the light of a person at the full range, and at the full range there is only just enough to make out a shape.
Whether a face is identifiable at any distance is set by pixels per foot, the same by night as by day. Our guide to how far a security camera can see works out both limits together, with a calculator for the lens and resolution and a figure for the night case. Smart IR, which most cameras now have, turns the LEDs down when something close fills the frame, so a person walking up to the camera does not turn into a white shape.
04Why security camera night vision is blurry or white: the reflection traps
When a night picture is a white haze with a dim person somewhere behind it, the camera is almost always seeing its own light. The LEDs sit a few millimeters from the lens, so anything just in front of them is lit far brighter than the person you care about, and it is lit from exactly the direction the camera is looking. The rule is the inverse square law: twice the distance, a quarter of the light. Figure 2 walks through the five traps and computes how lopsided the light is.
The underside of the overhang sits about a foot above the LEDs, lit from below and seen at close range. It fills the top of the frame with white, and the exposure drops to cope, so the person at the door goes dim.
What to doMount below and forward of the edge, on an arm if needed, or tilt the overhang out of the frame. If neither works, turn the camera's infrared off and light the spot another way.
(person ÷ near)²: (30 ÷ 1)² = 900
Something 1 ft from the LEDs gets 900 times the infrared per square foot that a person 30 ft away gets. If both reflect alike, it shows that many times brighter, so either it clips to white or the exposure drops and the person goes dark.
Where each trap hides on a building
- Eaves, soffits and door canopies. The most natural mount, tucked under an overhang out of the rain, is the commonest trap. Mount below and forward of the edge, on an arm if you have to.
- Piers, inside corners, downspouts and sign boxes. Anything beside the camera catches the edge of the beam. So does a fence or a parked truck a few feet in front of it. Bring the camera out on a bracket, or turn it to look along the wall instead of across it.
- Rain, snow and fog. The camera cannot fix these alone; the lit drops sit right in front of the lens. Light from somewhere else, below, is the answer, and detection set to people and vehicles keeps the alerts sane.
- Spider webs. A strand a couple of inches from the lens is the brightest thing in the scene. Clean domes and front glass as routine service.
- Glass. A camera behind a window sees its own infrared on the pane; our guide to indoor vs outdoor cameras covers that case.
The fix that covers most of them: light from somewhere else
Turn the camera's own infrared off and light the scene from a separate fixture, an infrared illuminator or a white light, mounted away from the camera: on another part of the wall, or on a pole. The near objects are then no longer the closest thing to the light, and the person gets the light instead. A fixture also lights more evenly than the small LEDs on a camera, and one fixture can serve two or three cameras looking at the same yard.
05Bright and dark in one frame: headlights, signs and lit windows
A city street at night is rarely dark everywhere. A lit shop window, a sign or headlights turning in sit in the same frame as a recessed doorway in shadow. A camera sets one exposure for the frame, so either the bright part clips to white or the dark part goes black. Wide dynamic range, WDR, combines a short and a long exposure to hold both. The example low light camera lists 130 dB. Decibels here are a ratio, 10 to the power of 130 ÷ 20, about 3 million to 1, but makers measure it in different ways, so treat the number as a feature check rather than a score.
Placement still does more than WDR. Point a camera along the street or the wall rather than straight at a light, and keep bright signs out of the top of the frame. The worst case in a building, headlights coming at a camera in a dark garage, is worked through in our guide to commercial security cameras for office buildings.
06Construction site security cameras at night in NYC
A construction site is the hardest night job a camera gets: no permanent power, no network, no light except what the site brings, and a structure that changes shape every few weeks. Cameras go on the fence, the sidewalk shed or a temporary pole. On an open lot a pole inside the fence is the usual answer, because it is high, it is out of reach, and it stays put while the shed and the fence move. We install temporary camera systems for construction sites and plan the night coverage with the site's lighting.
Figure 3 is the lot next to the example building, 150 by 100 ft. Pick where the pole goes, whether the structure is up yet and whether the pole carries a light, and see how each spot and a route through the lot would be recorded at night.
Swipe the plan sideways to see the whole lot.
- 1GateBlack and white, well inside the infrared37 ft from the pole
- 2HoistBlack and white, faint: outer half of the infrared96 ft from the pole
- 3Material laydownBlack and white, faint: outer half of the infrared60 ft from the pole
- 4Tool containerIn view but dark: past the infrared range160 ft from the pole
- 5Back fenceIn view but dark: past the infrared range119 ft from the pole
- 6Site office doorIn view but dark: past the infrared range124 ft from the pole
Infrared alone gives you movement in black and white, and only out to its range. A light on the pole gives you color near it.
A single pole at the front corner records the gate, the laydown and the hoist, and nothing on the far side: the back fence, the tool container and the site office door are past its infrared. Put the structure up and the back of the lot also goes behind it. Poles at the front and back corners together record every spot and the whole route at both stages, and the light on the poles is what turns black and white movement into color you can describe.
Light the gate and the material
Infrared on a pole shows that someone crossed the lot. It does not tell you what they wore or which truck pulled up to the gate. Where that matters, at the gate and over the material laydown, give the cameras visible light: a fixture on the pole, on a photocell or on all night, aimed into the lot and away from the windows across the street.
Power, network and recording on a site
Power comes from the site's temporary service, coordinated with the electrician, or from a solar and battery unit where there is no service yet. Size a battery for the longest night of the year: on December 21 New York gets about 9 hours and 15 minutes of daylight, so the cameras, the infrared or the light and the cellular router run on battery for close to 15 hours. Video goes out over a cellular connection. Record on site, on the cameras or a recorder locked in a box on the pole, and keep a copy or at least the alerts off site, so the record survives a stolen recorder. Our guides to cloud vs local recording and to what keeps recording in a power outage cover both halves.
Move the cameras as the building goes up
Figure 3 shows the problem with a plan that is only drawn once: the view that worked at excavation loses half the lot when the structure rises. Plan a second pole or a camera on the structure, re-aim as the floors climb, and look at every view again at night after each change. While the structure is open, plan the finished building's own cameras too; pathways, sleeves and the telecom room are far easier to provide before the walls close, which is where our structured cabling work starts.
07Test night vision at night: a checklist for each camera
A camera aimed by day can look perfect and still be useless at night. Look at every camera's live view after dark, at the spot itself, before you call it done.
- Is anything bright within a few feet of the lens: an eave, a wall, a gutter, a sign, a branch? Move the camera, tilt the surface out of the frame, or light the spot from a separate fixture.
- Does the person at the door show in color or in black and white, and is that what you need from this camera?
- At the far edge of what this camera has to cover, can you still follow a person moving through it?
- Does the camera flip between color and black and white at dusk, or when headlights or a sign come and go? Adjust its day and night threshold or its switch delay.
- Does a walking person blur? Cap the slowest shutter speed the camera may use.
- Is the night bitrate higher than the day bitrate? Size the storage for the night.
- Does rain or snow set off motion alerts all night? Light from elsewhere, or set detection to people and vehicles only.
- Are the dome and the front glass clean, and free of webs? Put them on the service list.
Two checks come before any drilling. In a co-op or condo, cameras in common areas usually go through the board and the managing agent, and our guide to NYC building security rules covers where cameras can look; it is general information, not legal advice. In a landmarked building or historic district, exterior work may still need Landmarks Preservation Commission approval.
Night cameras should also be wired where the building allows it. A wireless camera in a dense apartment building shares the air with every router around it, and the night picture, with its higher bitrate, is the one that suffers. Our guide to wired vs wireless security cameras works through when wireless is the right call.
FAQNight vision security cameras: common questions
How do night vision security cameras work?
Most switch to black and white at dusk: they move an infrared cut filter out of the way and light the scene with built-in infrared LEDs, light the sensor sees and people barely do. Low light color cameras keep the filter in and record color from whatever visible light is there, down to the level on their datasheet, then switch to infrared or turn on a white light when there is not enough.
Can night vision security cameras see in color?
Yes, where enough visible light reaches the subject. The example low light camera in this guide is rated for color down to 0.0003 lux at F1.0, and a street lit to the IES roadway targets gives thousands of times that. In a dark yard or lot, a camera records color only with its own white light or a fixture added nearby.
Why is my security camera night vision blurry or white?
Usually because the camera's own infrared is bouncing back from something close: an eave, a wall, a gutter, rain, fog or a spider web in front of the lens. Light falls off with the square of the distance, so a surface 1 ft from the LEDs gets 900 times the light of a person 30 ft away. Move the camera, tilt the near surface out of the frame, clean the lens, or light the area from a separate fixture.
Is 850 nm or 940 nm infrared better for security cameras?
850 nm reaches farther, because camera sensors are more sensitive there, but the LEDs show a faint red glow. 940 nm shows no glow, and one maker puts it at about 30 to 40 percent less effective, so its reach is shorter. Most security cameras use 850 nm.
How far can night vision security cameras see?
The infrared range on the datasheet, often around 30 m (98 ft), is how far the camera's light reaches, not how far it can identify a person. A person at half the rated range gets 4 times the light of one at the full range. Whether a face is identifiable is set by pixels per foot, the same by night as by day.
What security cameras work for a construction site at night in NYC?
Weather-rated cameras on a temporary pole or the fence, with infrared to show movement and a light over the gate and the material area for color. Power comes from the site's temporary service or a solar and battery unit sized for a winter night of close to 15 hours, and video goes out over a cellular connection with a copy kept off site.
Planning cameras that work at night?
The fastest way to know what a spot needs at night is to look at it. Contact Seneca Security with the address and the spots you want covered, and see our security camera installation and commercial security camera pages for the rest of the work.
Sources
- ANSI/IES RP-8-14, Roadway Lighting, Tables 4 to 7, as tabulated in the Texas Department of Transportation Highway Illumination Manual, Pedestrian AreasMinimum vertical illuminance targets: 1.0 footcandle for mixed vehicle and pedestrian areas with high pedestrian conflict, 0.1 footcandle for medium density residential streets. 1 footcandle is about 10.76 lux.
- Wikipedia, Lux, table of illuminance examples0.0001 lux moonless overcast sky, 0.002 lux moonless clear sky with airglow, 0.05 to 0.3 lux full moon on a clear night, 20 to 50 lux public areas with dark surroundings.
- NYC Department of Transportation, Street LightsNYC DOT has retrofitted almost all of New York City's streetlights with energy-efficient LEDs.
- A camera maker's datasheet for a standard infrared dome camera1/2.7 inch sensor, 2.8 mm F1.6 lens, color minimum illumination 0.005 lux (F1.6, AGC on), 0 lux with IR on, infrared range up to 30 m (98 ft), 850 nm.
- A camera maker's datasheet for a low light dual light bullet camera1/1.8 inch sensor, 2.8 mm F1.0 lens, color minimum illumination 0.0003 lux (F1.0, AGC on), infrared range 40 m and warm light range 40 m, 850 nm, 130 dB WDR, smart illumination.
- A camera maker's support article on infrared wavelengths850 nm LEDs show a faint red glow and most cameras are sensitive there; 940 nm LEDs show no glow and are about 30 to 40 percent less effective.
- timeanddate.com, New York sunrise and sunset, DecemberDecember 21: sunrise 7:16 am, sunset 4:31 pm, day length 9 hours 15 minutes.
- Inverse square law and the f-numberLight from a small source falls with the square of the distance; the light a lens passes to the sensor goes with 1 over the f-number squared. In any optics text, such as E. Hecht, Optics.
Have a project in mind?
Send us the address and the spots you want covered after dark. We walk the building, then send a written scope. Same-day quotes when we can. Licensed and insured.