Cobweb effect on IR mode

[bricklayer1807]

I've recently upgraded some of our cameras with Reolink PoE 5MP HD cameras, unlike the old cameras these have IR for night vision. I'm now getting multiple false triggers because for an hour or two during the night each of them starts displaying 'cobwebs' on the image, which shake and move enough to trigger recordings on BI. The first morning after this happened I went out to clean away the 'cobwebs' but there weren't any! Is this some sort of refracted light effect generated by the lens? Any other ideas? I've attached an image.

 

[alastairstevenson]

The first morning after this happened I went out to clean away the 'cobwebs' but there weren't any!

You'd hardly see them when the light isn't in the right direction to reflect back.
These are strands of spider silk, close to the sensor.

I'd guess you installed bullet format cameras, with a ring of IR LEDs around the sensor.
Spider webs are a well-known standard problem with that format.
Much better with turret format and the 'EXIR' type of single IR LED.

 

[bricklayer1807]

You were right! I went to look again and this time with my plus 2 glasses and a magnifying glass and then I could see there were some tiny strands of spider silk that I'd not spotted before. You're also right about my new cameras, so what is it about turret cameras and 'Exir' that stops them being bothered by spider silk? What can I do with my bullet cameras to keep the spiders away?

 

[sebastiantombs]

Best thing to do with those bullets is return them, if you can, and replace them with either a turret or modern bullet camera. The "secret" is that the IR LEDs in a turret are physically separated from the lens. The same is true of the newer bullet styles like the Dahua B5442 series. No camera with IR is totally immune from spider web problems, but turrets and the new bullets have far, far, fewer problems.

 

[bricklayer1807]

There are plenty of turret cameras out there with the ring of leds around the optical lens just like my bullet cameras, so I'm assuming it's the more modern type with a single lens for the led light which are considered to be much better when there is spider silk around. Why exactly is the single lens type so much less affected by cobwebs?

 

[sebastiantombs]

Bugs love infrared light. Spiders love bugs. When the IR LEDs are in a ring around the lens it's pretty obvious what happens. If the IR LED is a single, high powered, LED and mounted off to the side or below the lens, even if only by an inch or two, the area of interest for the bugs and spider is moved away from the lens. Keep in mind I am talking about a turret camera, not a dome camera. Look up the Dahua 5442 series and you'll see what the differences are, and if you buy one, you'll see what the differences are between a good camera and a Reolink, especially at night.

There are lots of threads here talking about spider problems. Some people use Vaseline, some use Vicks Vapo Rub, some use silicon spray, some use various bug sprays. All have recurring problems. I have eight turrets and four bullets. The only ones that I have spider problems with are the cheap bullets with LEDs around the lens. In fact I have a turret mounted in a tree and have never had to clean a spider web from it in over two years.

If the cameras weren't Reolink, you could also shut off the IR in the camera and install an IR illuminator separated from the camera. Problem is that low end cameras like Reolink, SV3C and similar, don't provide any way to control IR or a whole list of other key settings.