The Night Video That Was All Glare

Why this matters

A homeowner had a package taken from the porch at 21:30 and pulled up the driveway camera to find a white haze with a vague shape moving through it. The same camera's daytime video was sharp. The dealer had installed the system six weeks earlier, so the customer's first question was whether they had been sold a bad camera. They had not. The camera was lighting its own surroundings with infrared and looking at the reflection, which is a mounting decision, not a camera fault. Three cheap checks went first, each for a reason, and one of them nearly sent the tech home with the wrong answer.

The camera and the complaint

The camera was a dome IP camera powered over Ethernet (PoE, where the network cable carries power as well as data), mounted on the underside of the soffit at the front corner of the house, aimed down the driveway toward the street. It had a ring of infrared LEDs around the lens that switch on automatically in low light, and the image switches to black and white when they do. The fascia was about 4 in in front of the dome, and the gutter on the fascia hung with its bottom lip about 3 in below the soffit.

Daytime: clear, well exposed, the house number across the street readable. Night: the center of the frame washed to a gray-white glow, the edges dark, any person in the driveway a soft silhouette.

What could produce that picture

A washed night image with a clean day image has a short list of causes, and they are cheap to check in roughly this order.

Firmware or settings. An exposure or IR setting that over-drives the LEDs or holds the shutter open too long, or a firmware issue in the day/night switching. Checkable remotely in minutes.

The dome and lens. Dirt, a smear or a scratch on the dome bubble scatters light. In daylight the scene is far brighter than anything on the dome, so a smear barely shows. At night the IR LEDs sit right behind the bubble and anything on it is lit brightly from a few millimeters away.

IR leaking inside the housing. A dome camera has a foam or rubber ring between the lens barrel and the inside of the bubble. If it is missing or not seated, IR from the LEDs travels across the inside of the bubble and straight into the lens.

IR reflecting off something outside near the camera. A nearby wall, soffit, eave or gutter lit at close range by the LEDs looks brilliant to the sensor compared with a driveway 30 ft away, and the camera's automatic exposure darkens everything else to cope.

First pass: remote, the same afternoon

The service tech logged into the recorder and the camera. Firmware was one minor version behind the maker's current release, and the release notes mentioned day/night switching, so he updated it. The IR was set to automatic and the "smart IR" feature, which reduces LED output when a near object is very bright, was already on. Exposure was at its defaults.

The next morning he pulled the footage recorded overnight after the update. No change. That cleared the settings and the firmware, and it said something more useful: smart IR was already trying to turn the LEDs down and the image was still washed, so whatever was reflecting was very close or very reflective or both.

Second pass: on site, after dark

A night fault gets diagnosed at night. The visit was booked for 19:30, after full dark.

Ladder first. The soffit at that corner was about 11 ft up. The tech set an extension ladder on firm, level ground at roughly one foot out at the base for every four feet of working length to the support point, which is the setup the federal portable ladder rules describe in substance (29 CFR 1910.23 for general industry; 29 CFR 1926.1053 where the work is construction). He used a standoff so the ladder bore on the wall, not on the gutter, which would have bent and let the ladder slide sideways. A second person footed the ladder and held a work light on the base. He worked with a headlamp so both hands were free for the climb and he kept three points of contact while moving on the ladder.

Dome and lens. In daylight at install the dome had looked clean. At night, with the LEDs on and a flashlight held at a low angle across the bubble, it was not: a single strand of spider web ran across the lower half of the dome from the edge of the soffit, with a few dust particles strung along it. Lit by IR from a few millimeters behind, the strand and its dust were glowing. He wiped the bubble with a lens cloth, front and back of the strand, and checked the live view on his phone.

It improved. The center of the frame went from white to gray. It did not clear. This was the check that nearly ended the visit wrong: a technician who finds a web and sees an improvement tends to stop there.

Inside the housing. He opened the dome. The foam ring was seated around the lens and pressed against the bubble all the way round, so IR could not travel across the inside. He closed it and re-tightened the screws evenly so the ring stayed compressed.

Outside the housing: the decisive test. He took a piece of matte black card from the van, held it flat against the underside of the soffit between the camera and the fascia so it blocked the LEDs' view of the soffit, fascia and gutter, and watched the live view. The haze dropped sharply and the driveway appeared. He moved the card away; the haze came back. He held it again with the ladder steady and his helper watching the phone; same result twice more.

The picture was the camera seeing its own IR bounce off the painted soffit and fascia a few inches away and off the bottom lip of the gutter, which hung across the very top of its field of view.

The geometry

 SECTION AT THE EAVE, AS FOUND (not to scale)

        roof deck
   =========================+
                            | fascia
   soffit ------------------+--+
         [DOME]  <-- 4 in --|  | gutter, lip
          | \  IR spill     +--+ 3 in below soffit
          |  \ lights soffit, fascia and
          |   \ gutter lip a few in away
   wall   |    \  bright reflection back
          |     \ into the lens
          |      view down the driveway

 AS CORRECTED
   soffit ------------------+--+
          |                 +--+
          | drop bracket
          |  12 in below soffit, 8 in
          |  out from the wall
         [DOME] -> IR and view clear of
                   soffit, fascia and gutter

A camera mounted tight to a soffit looks good from the street and is protected from rain, which is why installers do it. But an IR ring lights everything within its spread, and anything a few inches away is far brighter to the sensor than the scene it is meant to show. Light-colored paint, aluminum gutters and glossy fascia boards are the worst offenders.

The fix

Drop the camera below the soffit line. The tech fitted a drop bracket with a junction box at the top, fixed to the wall just under the soffit, that held the camera 12 in below the soffit and about 8 in out from the wall. At that position the bottom lip of the gutter sat 9 in above the dome (12 in minus the 3 in it hung below the soffit), and the soffit and fascia were out of the top of the frame and out of the close-range spread of the LEDs.

Keep the cable weathertight (see related: How to Mount and Weatherproof an Outdoor IP Camera). The cable came down through the existing soffit hole into the top of the junction box, so it never ran exposed. The connection inside the box used the camera's own weatherproof cable gland, and the soffit hole was sealed around the cable, as were the screw holes from the old mount. Drip loops and entry from below are what keep water from running down a cable into a camera; with the cable entering from above, the gland and the sealed hole do that job.

Power off before disconnecting. He unplugged the camera's cable at the PoE switch before disconnecting it at the camera, so nothing was live while he worked the connector on the ladder, and plugged it back in only after the camera was mounted.

Re-aim and re-check. With the camera at its new height he re-aimed it down the driveway, keeping the street edge in the frame, and checked that the top of the picture now showed the driveway and street rather than any part of the house.

The finish test

The proof is a night image of the thing the camera is for.

• Live view at 20:40 with IR on: no haze. The driveway gravel, the street edge and the mailbox about 40 ft away were distinct.
• His helper walking up the driveway from the street: a recognizable person at the mailbox, and a readable face at about 15 ft. Whether a face is identifiable at a given distance is a question of pixels on the target, which the lens and resolution settle; see related: Camera Field of View and Pixels per Foot.
• Black card held near the camera at the new position: no change to the image, which confirmed nothing close was reflecting anymore.
• Recorded footage played back from the recorder, not just the live view: same quality. The recorder sometimes stores a different stream or bitrate from what the live view shows, and the stored footage is what the customer will need.

He left the smart IR on. He also logged the web, because a camera under an eave collects spiders, which build where insects gather around the camera. A web strand across a dome is one of the most common causes of a camera that was fine and suddenly is not at night.

What to take to the next install

Mount the camera where its IR has nothing to light within the first few feet except the scene. Under a deep soffit, that means a drop bracket or a wall mount below the soffit line, not the soffit itself. Where the customer insists on a soffit mount for appearance, set the camera at the outer edge so the fascia is not in front of it, or turn the onboard IR off and light the scene with a separate IR illuminator mounted away from the camera, so the light comes from a different point than the lens.

And at night, when a picture improves after cleaning, keep testing until it is right rather than until it is better.

References

• 29 CFR 1910.23, portable ladders in general industry
• 29 CFR 1926.1053, ladders in construction work
• See related: Camera Field of View and Pixels per Foot
• See related: How to Mount and Weatherproof an Outdoor IP Camera
• Camera manufacturer installation guide for mounting, IR range and housing gasket