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 Post subject: IR Leakage to Lens
PostPosted: Mon Mar 20, 2017 4:34 pm 
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Hi everyone - this is my first post.

Does anyone have any feedback on this problem I am having up here in Calgary? I have a residential NVR system with 7 POE cams. It's reasonably good quality from a devoted commercial security shop here...not cheap stuff as a package deal. All works well down to -35C (which shows they aren't cheapo cams).

One of my units looks between my house and the neighbour's house. Both of our homes have light coloured vinyl siding that reflects IR (I know, bad, bad, bad). But my issue is that when the camera dome is on, everything is washed out. When I remove the dome, everything looks great. So the Sherlock Holmes in me says the problem isn't the light coloured siding, but the IR leakage to the lens inside the LEDs that encircle it.

Thinking this way I attempted to isolate the lens further than what is provided by the internal foam ring between the lens and the surrounding LEDs using an additional foam O-ring I made myself. It helps, but is nowhere near the quality I get when the dome is removed altogether.

I'd love to be able to selectively disable LEDs to test if TOO much light is the problem, but my cam (I and think most cams) don't allow this. I could open it up and de-solder every second LED or so to test this theory, but I am not sure if leakage of the remaining ones would cause the same problem.

Another approach I was thinking of is to drop the camera closer to ground level and aim it up (instead of down from 12 feet or so) so as to avoid some of the reflection from the white siding.

For the record, everything during the day looks great, and all my other cams are fine at night. I have explored the option of supplemental lighting in the area and do have a strong (2200 lumen) LED motion light there as well. When it turns on this solves the problem when the IR LEDs in the cam disable, but this causes two new issues: 1) the delay makes me miss the event in question 2) the light triggers constantly as the area has two clothes dryer vents and two garage space heater vents that trigger the motion light constantly at night and annoy the neighbours.

I am attaching two pics -- one with the dome off and one with it on.

Any help from forum members would be appreciated. Is my troubleshooting sound here, or am I completely missing something? Thanks all.


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 Post subject: Re: IR Leakage to Lens
PostPosted: Mon Mar 20, 2017 6:58 pm 
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Would it be possible to disable IR totally on the camera and use an external IR light? Something like this one, so you can adjust the beam. http://www.ebay.com/itm/111722615701?_t ... rmvSB=true


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 Post subject: Re: IR Leakage to Lens
PostPosted: Mon Mar 20, 2017 7:33 pm 
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51cent wrote:
Would it be possible to disable IR totally on the camera and use an external IR light? Something like this one, so you can adjust the beam. http://www.ebay.com/itm/111722615701?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT&rmvSB=true


Being able to narrow the angle might, as this type of source supposedly allows, solve the problem. Good thought. sadly I can't disable the IR from my software, so either way I am disconnecting the LEDs on the board. But you may be on to something. :D


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 Post subject: Re: IR Leakage to Lens
PostPosted: Tue Mar 21, 2017 1:45 pm 
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Hi. Instead of taking camera apart.... remove some and cover the IRS on the right side (looking from cam front) with black electrical tape then replace dome then see what its like


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 Post subject: Re: IR Leakage to Lens
PostPosted: Tue Mar 21, 2017 10:42 pm 
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tomcctv wrote:
Hi. Instead of taking camera apart.... remove some and cover the IRS on the right side (looking from cam front) with black electrical tape then replace dome then see what its like


Won't the IT rad (heat) from the LEDs damage something if I do this? I had an indoor camera years ago that I aimed through a glass window to the outside and the heat reflected back and destroyed the cam.


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 Post subject: Re: IR Leakage to Lens
PostPosted: Wed Mar 22, 2017 2:59 am 
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CalgaryGuy wrote:
tomcctv wrote:
Hi. Instead of taking camera apart.... remove some and cover the IRS on the right side (looking from cam front) with black electrical tape then replace dome then see what its like


Won't the IT rad (heat) from the LEDs damage something if I do this? I had an indoor camera years ago that I aimed through a glass window to the outside and the heat reflected back and destroyed the cam.



No heat to talk about.


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 Post subject: Re: IR Leakage to Lens
PostPosted: Fri Mar 24, 2017 5:30 am 
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Not many dome cameras out there that do a good job with IR. Not even high end. A bullet camera is your friend when it comes to IR.


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 Post subject: Re: IR Leakage to Lens
PostPosted: Fri Mar 24, 2017 11:07 pm 
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ssmith10pn wrote:
Not many dome cameras out there that do a good job with IR. Not even high end. A bullet camera is your friend when it comes to IR.


Hummm...most of the bullets I've seen share the same layout of a single protective shield covering a lens that is isolated from the IR LEDs by a foam seal or ring. But I understand where a different setup with no chance for leakage could solve my problem. I'll have to research bullets more I guess :)


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 Post subject: Re: IR Leakage to Lens
PostPosted: Sat Mar 25, 2017 6:07 am 
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Electrical tape over IR. or use a black marker on each ir till intensity has been lowered


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 Post subject: Re: IR Leakage to Lens
PostPosted: Sat Mar 25, 2017 8:00 am 
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Another option would be a turret/eyeball style camera. It won't have the dome problems or the bullet camera spider problem.
Or you could leave the camera in day mode all the time and use the 2200 lumen motion light. The delay might not be as bad, but you might not see much until the light come on.


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 Post subject: Re: IR Leakage to Lens
PostPosted: Sat Mar 25, 2017 1:14 pm 
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51cent wrote:
Another option would be a turret/eyeball style camera. It won't have the dome problems or the bullet camera spider problem.
Or you could leave the camera in day mode all the time and use the 2200 lumen motion light. The delay might not be as bad, but you might not see much until the light come on.


I'm going to try the electrical tape option this weekend if the weather holds out and I don't have to fight wind and snow on a ladder. Sadly my cameras don't have a software switch for day mode.


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 Post subject: Re: IR Leakage to Lens
PostPosted: Thu Apr 06, 2017 2:06 am 
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Update 2017 Apr 05

Hi everyone. Thanks to all for your kind help. Attached is the latest result pic. When I went to try masking the IR LEDs I noticed that both the stock foam washer, as well as the additional one I added a year ago, had deteriorated significantly. These are the washers that isolate the lens from the LEDs. I have always wondered if leakage was the culprit. Maybe our Canadian winters are too hard on these foam components.

So, in a completely unscientific manner that would upset any analytical types on this forum, I addressed both at the same time. First, I removed the stock and additional foam washers that had failed and replaced them with a material a neighbour of mine provided: rubber backed silicone. He worked in the HP gas industry and had some left over. Actually, any high quality rubber/silicone should work, but the rubber side was textured to allow for glue which eases placement when reinstalling the dome. (Hint: mark the location of your lens with a tile or wax marker on the outside of the dome prior to removal. This helps greatly in aligning things later when trying to snug the fatter washer between the dome and the lens.)

Then I masked off 25%, and later, 50% of the LEDs. But before doing this I used a Fluke 63 IR Thermometer to check the temperature. I measured it in four different places as I know the dome will give a unreliable result. I saw only a 2 degree C rise with 25% of the IR covered and a 5 degree rise with 50% covered up. Not significant enough to worry about since the high end of my cams is well past what we worry about in Alberta. Here low end (-40C) is our concern. For now I am using high quality 3M electrical tape to mask, but will need to monitor this throughout the seasons. If it proves to be a maintenance issue then I will desolder the parallel-connected LEDs on the PCB. Thankfully the LEDs are not surface mounts--but are nonetheless small enough that I will need to back off on the caffeine the day I do the solder sucking. No way to get snips in there :(

Anyways, you can see the very positive result in the pic! It's almost as good as without the dome now. Was it the masked LEDs? The isolating silicon washer? Oooops....I also cleaned the dome as well...just to complicate the experiment more. (I've noticed that a "star-like" pattern, or any symmetrical pattern for that matter, on my video screen is almost always indicative of dust/moisture on the dome.

Lessons Learned:

1) try cleaning domes and lens routinely just in case this makes me think I have a bigger problem
2) isolating washers likely leak over time and need to be inspected as part of routine maintenance (see #1 - cleaning)
3) too much IR light CAN be a bad thing
4) never haul my fat *ss 250 lbs on to a 12 foot step ladder when the ground is in spring thaw and the ladder can sink
5) it hurts to fall from 12 feet


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 Post subject: Re: IR Leakage to Lens
PostPosted: Sun Apr 09, 2017 12:44 am 
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Definitely better! I think if it were mine I would consider separating the IR from the camera and having a separate enclosure for the IR. The board will likely be just a two pin plug that accepts the same 12vDC with a light sensor to switch it on and off. The area where it could be tricky is that some cameras will not open the IR filter unless it receives feedback from the IR board.... Cams that have an OSD menu seem to have a way around that but older cameras do not. That said id you have the IR at a slightly different spot but similar angle, you get the best of both worlds including reduced false triggers from moths flying close to the cam at night. Just have the IR spaced away a few feet and that has helped me a lot! If you really wanted to do this but have an older camera that needs the feedback from the IR board, I have a diagram for a circuit that will supplement the board and give you an adjustable IR cut trigger point.


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 Post subject: Re: IR Leakage to Lens
PostPosted: Sun Apr 09, 2017 11:06 am 
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justsomeguy wrote:
Definitely better! I think if it were mine I would consider separating the IR from the camera and having a separate enclosure for the IR. The board will likely be just a two pin plug that accepts the same 12vDC with a light sensor to switch it on and off. The area where it could be tricky is that some cameras will not open the IR filter unless it receives feedback from the IR board.... Cams that have an OSD menu seem to have a way around that but older cameras do not. That said id you have the IR at a slightly different spot but similar angle, you get the best of both worlds including reduced false triggers from moths flying close to the cam at night. Just have the IR spaced away a few feet and that has helped me a lot! If you really wanted to do this but have an older camera that needs the feedback from the IR board, I have a diagram for a circuit that will supplement the board and give you an adjustable IR cut trigger point.


Thanks. I like your idea. I have on order another camera and once I get it I will have one to play around with more. I also have a bunch of IR LEDs from another project years ago. I just need to build an op amp modulator for it and add a weather proof enclosure and light sensor. Or I can probably do both with an Arduino. When I put a scope on my working cam I saw the PWM signals are about 38 KHz, which I think is pretty common. I didn't know about issue with the IR filter being opened though. That's news to me...but mine do have OSDs.

Another benefit of your approach relates to my original post. In the area mentioned there are two dryer vents and one garage NG vent. In the winter these trigger the third party devoted IR lights that are combined with motion sensors (like the type you find on Amazon or eBay). But your approach of just using an ambient light sensor that turns on with nightfall would solve that. If I used an old school photocell (resistor type) I wouldn't need a trigger mechanism...it would be turn on and off with nightfall and daylight. I like it :)

Sherlock Holmes used to say, "This is a two-pipe problem." I think this is a two "Rum and Coke problem."

Thanks for the idea @justsomeguy!


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 Post subject: Re: IR Leakage to Lens
PostPosted: Sun Apr 09, 2017 2:58 pm 
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Sounds good, so the issue I had was that I had a camera behind a window so at night the glass would reflect the IR, so the solution was to put the IR outside. When I opened up my camera, as with most cameras, the IR leds are all on their own board that just unplugs and has its own power circuitry already on that board with the photocell. Once the photocell tells the board to turn on, there is a one wire connector that goes back to the cam with a 3v signal to tell it to open the ir filter.

Without that signal, the way I have seen a camera be able to do it is by setting a threshold for the AGC. If the camera has to up the Gain by X amount, then it is time to open the ir filter.

You would likely be able to use the existing board for your external IR source but if you have more IR leds then great! I know that they all have a rated ma and the secret is getting a fixed current driver matched to the amperage amount that is within the spec output voltage for said driver. There are great deals on ebay for high power IR leds and drivers. While the 850nm leds are better bang for buck, at night they really jump out at you! 940nm is much less likely to make you seem like a wierdo to your neighbors for flooding the street in IR :D

Anywho, cheers and good luck on the ladder next time!


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