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Camer w/Auto-iris lens can't adjust for light properly
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| Scruit |
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Posts: 445
Joined: 25 Nov 2006
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Posted: Sun May 11, 2008 11:57 am
Post subject: Camer w/Auto-iris lens can't adjust for light properly
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Camera is a Focus Micro FM-25323 1/3CCD 470TVL. Lens is a 60mm DC.
Power supply is a regular 12VDC regulated (12.7v unloaded). Tried running it from a 12v battery - same thing.
The camera seems to be really struggling to keep a consistent light level. Sometimes it's far too bright, sometimes too dark. See:
 
These two images were taken just minutes apart.
When it changes from light to dark it does so very slowly, over a couple minutes. Most of the time it's too light.
Case in point - right now it looks like this:
When it was too bright I tried adjusting the DC level down. The picture had the right brightness and contrast but was very grainy and speckly like you get with a fixed-iris camera as the light level drops.
Seems to me like the auto-iris lens is just not keeping up withthe light changes. The annoying thing is that it's very dark and overcast today so the lens is opening up WAY too much. But if the lens wasn't working at all then the image would be just black / lens fully closed, right?
Questions:
1) Is it ok to use AGC at the same time as using a DC auto-iris lens - or should the lens be able to compensate for light changes on it's own?
2) Anything else I should look at?
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Scruit
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| CameraGimp |
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Posts: 107
Joined: 10 Oct 2007
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Posted: Sun May 11, 2008 1:31 pm
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It is ok to use AGC with a DC lens but I set the level with it off. Here is how I would set it
Assuming daylight.
Turn AGC off
Turn electronic iris or AES off.
Check DC lens opens and closes, flick level to min then to max. The video should go black without AGC noise and then it should white out. If it doesn't check EI and AGC are off.
Set DC level. You want 1v pk-pk on a typical scene, if you don't have the equipment you can set it with your eye.
Turn AGC on and check the video doesn't change. If the picture get brighter you haven't set the level right (or there is a fault). AGC is slow to act so I is easier to see when you turn it off. Turn AGC on, wait 5 seconds, flick AGC off. If the video level drops then AGC was working and you have a problem.
Turn AGC on and check it, pop your hand in front of the lens and look for noise.
If you do that and the camera still misbehaves then I'm lost.
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DarkData (UK) Online Digital Backup
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| Scruit |
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Posts: 445
Joined: 25 Nov 2006
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Posted: Sun May 11, 2008 1:49 pm
Post subject:
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| CameraGimp wrote: |
It is ok to use AGC with a DC lens but I set the level with it off. Here is how I would set it
Assuming daylight.
Turn AGC off
Turn electronic iris or AES off.
Check DC lens opens and closes, flick level to min then to max. The video should go black without AGC noise and then it should white out. If it doesn't check EI and AGC are off.
Set DC level. You want 1v pk-pk on a typical scene, if you don't have the equipment you can set it with your eye.
Turn AGC on and check the video doesn't change. If the picture get brighter you haven't set the level right (or there is a fault). AGC is slow to act so I is easier to see when you turn it off. Turn AGC on, wait 5 seconds, flick AGC off. If the video level drops then AGC was working and you have a problem.
Turn AGC on and check it, pop your hand in front of the lens and look for noise.
If you do that and the camera still misbehaves then I'm lost. |
The first thing I tried (before reading your response) was to swap two cameras over. The 60mm lens is now on a different camera and once the rain stops for a moment I'm gonna put it up. From there I can see if the light fluctuations follow the lens or the camera.
If there's still a problem then I'll go through your steps above. Thanks for the response!
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Scruit
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| RickA |
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Posts: 611
Joined: 28 Sep 2007
Location: Kentucky
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Posted: Tue May 20, 2008 3:54 pm
Post subject:
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Might want to check for a video/dc switch on the camera also.
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Pegasus CCTV Tech support Rick www.pegasuscctv.com
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| Kiwi |
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Posts: 215
Joined: 03 Sep 2007
Location: New Zealand
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Posted: Tue May 20, 2008 4:29 pm
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Either wiring between camera and iris is faulty, or the iris has oil on it or some other obstruction to operation.
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AVtech 782 with JVC TK-C925U true day/night (home system)
Arecont 3130 (outdoor webcam)
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| vin2install |
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Posts: 39
Joined: 30 Apr 2006
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Posted: Thu May 22, 2008 5:26 pm
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I've seen this sometimes when I'm fixing cameras at camera company manufacturer i work for . To test if its the lens then pull the Iris plug from the back then if you see a completely black screen then your lens is ok and your camera's iris control is broken. If you see a image then still then it would be your lens would be defective.
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