Night time looks foggy on IR cams

[majortom 0]

I have been working with some Hunt CCTV IR cameras at a particular project where the picture at night looks extremely foggy (when there is no fog). On one of the cameras, I was able to get results by moving the camera up a wall 10'. I have not yet moved the other 2, but have temporarily replaced the Hunt IR Domes with Hunt IR Bullet cameras at same locations and the fog at night continues.

I am trying to imagine what it is in the picture that causes the difference, when the domes I brought back to my place seem to work OK here.

 

Is it most likely that I do not have enough IR? Too much IR?

Too much contrast between light areas and dark areas?

Hunt thinks that if I move the others (even a few feet) that I could resolve the issue. But I am looking for an overall rule for the future, as to how to avoid this issue.

[GrouchoBoucho 0]

hard to tell without pictures, but it's probably the ir reflecting off the inside of the camera glass or dome.

[majortom 0]

The Hunt Domes have a spring loaded, circular separator between the IR emitters and the lens, so this is hard to imagine.

It IS a little worse when the cover is on, but I found that by turning down the low light luminescence from .75 to.25, it seems to help quite a bit.

[majortom 0]

See the day and night images at http://www.groundcontrolsatellite.com/index.php/11g28did-upload

[majortom 0]

I also added some cam 4 shots from same backyard.

Password for page is "CCTV"

[MaxIcon 0]

I have some IR cams that are fine out on the bench, but get a lot of IR fog when mounted due to the IR reflecting off of the walls and back to the dome.

 

You can check if this is the problem by pointing it straight out from the wall (assuming there are no eaves close that would reflect it). If this makes the fog go away, wall reflections are your problem. If it's still there, it's more likely to be internal reflections on the dome.

 

If the lens has anything on it (front or back element), like films or fingerprints, this can also pick up the IR and fog up the view, while looking good during the day.

[yakky 0]

Silly question, but did you focus them at night when the aperture is wide?

[survtech 0]

We don't understand the problem. It looks clear to us.

 

[majortom 0]

When they were at clients home, I focused during the day.

When I am working on it at my place, I have focused at night and come up with similar scenario (focused at night).

 

I might not have mentioned it before, but I temporarily replaced the domes at the clients with 79G Bullet IR cameras and the same fog effect occurs. So it cannot just be reflection off dome cover. Maybe reflection off a wall.

 

But, again, when I brought the domes back here, I was able to recreate similar effect, that is worse with cover on, but is mostly remedied by turning down the low light luminescence seting from .75 to .25.

I picked up Hunts better dome that is WDR and 650 lines in both an IR and non IR version that I hole to test here tonight.

[majortom 0]

I had thought that I had it. Got new dome covers, made sure they were pristine, set low light luminescence to .25, and there was still fog and picture was too dark. Looks like I have to move the cameras or it is reflection from the dome. Problem does not exist without dome covers on.

[MaxIcon 0]

Sounds like it's reflecting from the wall back to the outside of the dome, and there's not a lot to be done about that except maybe disabling the onboard IR and using a separate IR illuminator that points away from the wall.

 

Another option would be to disable the IR and use motion detector white lights, though this can have downsides too.

 

If you're a hardware hacker, you could look at cutting a hole in the dome for the lens and sealing it to keep moisture from inside the camera. That could be tricky, though, and if you're exposed to the weather much, you might end up with dust and water spots on the lens.