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 Post subject: IR vs Night Vision
PostPosted: Mon Oct 05, 2009 1:23 pm 
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Hi guys, I have a question?

What is the difference between IR and night vision.
I know that night vision leaves a slight green glow when looking at the image on the monitor but I am interested in differences in specs.

I want to google it but I know you can answer my question much better. I worked only with IR till now.

Thank a lot,
Tomislav


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PostPosted: Wed Oct 07, 2009 6:46 am 
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An IR-sensitive CCTV camera is a completely different technology compared to military night vision. The latter is much higher resolution, and much more sensitive. Also, the latter will only last about 5000-10000 hours on an intensifier tube (the heart of a set of NVGs).

Military "Night vision" is also several times the price... but the performance difference is noticeable.

To illustrate this, here are a series of pictures. The day picture is only for reference, and the night pictures were all taken at exactly the same time, and under exactly the same environmental conditions.

Day picture:
Image



Night picture (camera has built-in IR LEDs) but they're totally underpowered for this scene. The far trees in the scene are over 100 yards way, and this little IR bullet just doesn't put out enough light. This scene is pitch-black to the naked eye.
Image



Night picture through a Speco Intensifier (slowest shutter speed). You can make out some things, but the slow shutter speed completely smears anything moving:
Image



This is military night vision. American Generation III:
Image




This is military night vision looking at that scene with that little IR bullet camera operating (the one I mentioned earlier). Note the IR has brightened up the foreground of the scene. The camera can't see the IR, but the NVGs most certainly can.
Image


Appreciate the difference now?

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PostPosted: Wed Oct 07, 2009 1:41 pm 
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Yes this is impressive.

I tried to explain some people the difference between these two but also I am not very familiar with technical data. Most of the people who do not work with CCTV just say night capability and this is it, they do not know that it is a bit more then just that...IR, night vision, different IR (850, 940)...etc so I tried to find out a bit more.

Thanks a lot....


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PostPosted: Sat Oct 17, 2009 3:27 pm 
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Hi Sawbones .. thanks for making this illustration so clear!

I just like to add a few questions:

1) Was told by my supplier IR LEDs have a "limited" lifespan. It about 18mth to 24mth .. is this true?

2) If I point a long range (About 40m / 120ft) IR cam at a very near object .. there is a very bright spot .. like a spotlight .. is this a normal situation? Or are there more intelligent cameras that will adjust the IR intensity accordingly?

3) There are situations where IR don't seemed to come on early enough .. the monitored area is rather dim .. but the object .. a car .. is brighter .. but the number plate is not bright enough to be identified .. How can I tweak this? Is it a inherent limitation of most IR cameras?

4) Is there a diff in the technology of Night Vision vs Day/Night Cameras? Ok .. this sound dumb but .. forgive me as I m very new in the industry :)

5) Under what will recommend a Day/Night Camera (0.01 Lux) vs an IR Cam?

Thanks


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PostPosted: Sun Oct 18, 2009 9:01 am 
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ryeporta wrote:
Hi Sawbones .. thanks for making this illustration so clear!

I just like to add a few questions:

1) Was told by my supplier IR LEDs have a "limited" lifespan. It about 18mth to 24mth .. is this true?

2) If I point a long range (About 40m / 120ft) IR cam at a very near object .. there is a very bright spot .. like a spotlight .. is this a normal situation? Or are there more intelligent cameras that will adjust the IR intensity accordingly?

3) There are situations where IR don't seemed to come on early enough .. the monitored area is rather dim .. but the object .. a car .. is brighter .. but the number plate is not bright enough to be identified .. How can I tweak this? Is it a inherent limitation of most IR cameras?

4) Is there a diff in the technology of Night Vision vs Day/Night Cameras? Ok .. this sound dumb but .. forgive me as I m very new in the industry :)

5) Under what will recommend a Day/Night Camera (0.01 Lux) vs an IR Cam?

Thanks


1. LEDs have a very long life... longer than conventional bulbs. This assumes, however, that they're not being driven too hard... since too much voltage and heat will kill them. That's what happened to the two illuminators on the right in this picture:

Image

2. You're referring to the "spotlight" effect. Too much IR in the center of a picture (by a strong IR source) will wash out the rest of the picture... like this:

Image

3. Some higher-end cameras will allow you to set a light level at which the IR comes on... lower end cameras don't have this feature.

4. NVGs are a completely different technology. They amplify ambient light with several different technologies. A CCD security camera is simply a sensor that is sensitive to light, but doesn't involve an intensifier tube like an set of NVGs. Here is an explanation of NVG technologies:

http://www.morovision.com/hownightvisionworks.htm

5. A true day/night camera contains an IR-cut filter. Ignore the "Intensifier" claims of Speco and other vendors that simply slow down their shutter speed to gather more light. If you want real day/night, you're looking at a camera that switches to black-and-white mode at night when the IR-cut filter is automatically removed in response to lower-lux conditions.

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 Post subject: low-lux?
PostPosted: Sat Oct 24, 2009 2:32 pm 
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Why not low-lux camers? Remember if the camera cant see, neither can the mutt robbing the place. Plus there is no tell-tale red led hue noticable near the camera. Why not wash the area with a separate IR led iluminator then cover the area with low-lux cams. Many times the ambient street lamps or even a near full moon gives off enough light to get a great pic..

pyro


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PostPosted: Sat Oct 24, 2009 2:41 pm 
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It all depends on the camera specs.Some manufacturers say that their cam does well in low light,but YOU have to actually test the cam in your environment.Many have been disappointed!


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PostPosted: Sat Oct 24, 2009 4:51 pm 
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ryeporta wrote:

I just like to add a few questions:

1) Was told by my supplier IR LEDs have a "limited" lifespan. It about 18mth to 24mth .. is this true?


LEDs can last years as long as they're not overdriven. Voltage isn't the main killer - current is. You can put any voltage you want across an LED as long as you limit the current with an appropriately-rated resistor (you can also use a constant-current power supply if you want to get REALLY fancy).

Allowing the LED to draw more current means it will shine brighter... but for a shorter time. "The light that burns twice as bright burns half as long... and you have burned so very, very brightly, Roy."

Quote:
2) If I point a long range (About 40m / 120ft) IR cam at a very near object .. there is a very bright spot .. like a spotlight .. is this a normal situation? Or are there more intelligent cameras that will adjust the IR intensity accordingly?


This is normal. Take a look at an LED flashlight - turn it on, point it at the wall. IR LEDs are no different except for the spectrum of light they produce.

If you look inside a typical LED (not while it's on, obviously), you'll see the light-producing semiconductor junction is inside of a small cup-shaped reflector - this directs most of the produced light straight forward, just like a light bulb inside a standard flash light housing. Thus, they don't blast light out in all directions like a standard light bulb.

Quote:
5) Under what will recommend a Day/Night Camera (0.01 Lux) vs an IR Cam?


IR LEDs are really no different, functionally, than having a flashlight attached to your camera, except they use a non-visible wavelength of light, so they're not as noticeable, and they don't illuminate the area for the naked eye. Like a flashlight, they have limitations - they're limited in the distance they'll shine vs. the area they'll cover. If you make a tighter beam, you can get more distance, but cover a smaller area. Or you can use a wider coverage, but get less distance. They're great for NO-light situations, within their range... but if you need to cover a larger area and will have SOME ambient light (streetlights, say), you might find a D/N camera that can properly display with the low light, will work better.

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 Post subject: Re: IR vs Night Vision
PostPosted: Sun Jan 01, 2012 2:17 pm 
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This thread should be a sticky if it isn't already!!
Thanks for the enlightening information. :)


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