CameraGimp

Hi there, You need to turn electronic iris on, this allows a camera to cope with bright light when you don't have a lens with a motorised iris. Electronic iris simulates the iris closing by increasing the shutter speed of the camera, in effect closing it's eye for a fraction of a second. It may be called something other than electronic iris but it will be there. If you use EI you can open your lens iris fully and the image will not white out in sunlight, and you won't harm the low light performance. Personally I set the iris a touch back from fully open as some lenses can lose a bit of sharpness when fully open but that may just be me. Pat.

In my world DC iris level adjusts the iris of a DC lens. Setting it too low can result in AGC noise being visible but that only happens as a consequence of the lens iris being closed and it not letting enough light through. I've no experience of this camera and it may be labeled incorrectly but DC iris level shouldn't increase the max gain.

As zmxtech has pointed out the camera is applying too much gain to the highlighted areas. This is causing them to flare, but it does it as the average of the scene is dark. If you increase the lighting in the scene the camera will apply less gain and hence less flare. Other alternatives are to try setting the gain down. I think it is a setting on that camera. This will make the scene darker but it should reduce the flare. I remember the SD II camera had a 48 grid blc, that could also help if it is on your camera. If it is you need to tell the camera to weight the areas with the lights more than the areas without. This can reduce the gain applied. Last one, if you have a video iris lens it will have a Pk-Av adjustment. If so adjust it to Pk, this will force the camera to expose the peaks at the expense of the average. That would reduce the flare.

You say the picture is grainy even in broad daylight. This sounds like AGC noise. Automatic Gain Control is an amplifier for video. It should boost the video at low light. If you are seeing it during the day I would suggest the lens is closed down. Have a look at the DC level adjust. You should turn agc off when you set dc level. Make sure to turn AGC back on after you've finished.

First thought. The number plate is blurry....Is it focused? Seriously if it is blurred at night with lights off but ok with floodlights on it sounds like a focus issue. If your camera has a motorised lens then you need to focus the camera when the lens iris is fully open. This is due to depth of field reducing as the iris opens. You can either focus it at night or put a filter in front to simulate low light. As to the issue of not being able to read a number plate at xx feet. There are two things that will influence resolution. The resolution of the camera and the field of view. The resolution is going to be pretty fixed, I'd guess you bought a high res camera with 480TVL? If that is the case changing camera isn't going to make things better (much). Field of view. A camera a 100m away with a big zoom could have a better resolution of a number plate than a camera that is 20m away with a wide field of view. So the question is how large is the number plate as a ratio to screen size?

I can't find an english manual but the specification shows DSS and digital noise reduction. Both of these could make a big difference at low light as could the lens level.

A grainy picture means AGC is working. If that is happening during the day then it sounds like the lens is closed or the camera is working at a fast shutter speed. I'd turn flickerless off unless you have a reason to have it on then look at the lens. Does the camera have a manual or a motorised lens? If it's manual it needs opening and AES or EI needs to be turned on. If it is motorised then make sure EI is off. If it is then adjust the lens level. When you do that turn AGC are off and adjust the lens level usually via a pot on either the camera or on the lens. Do this during the day. When the level looks right turn AGC on and check the level doesn't change, if it goes up you've set the level too low.

Hello wildpete, The first bit is simple, you should be ok putting two cameras on a four camera system. As for the am I crazy question it is harder to say. I'm not an installer but I know a lot about cameras and would have no problem setting them up and often have when I've been called out to problem sites but what I would have problems with is selecting the right lens, and lamps or even the best place to site them. So I'd say you may be able to do the job yourself and use the saved money to buy better equipment but be careful as there is more to installing good CCTV, especially when working with IR, than getting the best equipment. Have I as a techie just said something nice about installers? Time for a lie down me thinks.

Hi there, Can you clarify some thing for me Is the glare you are referring to the lights on the house over exposing at night, and if so is the camera applying gain (AGC), ie grainy picture when this is happening?

I was part of a team that brought a camera out based on the first Pixim chipset and was very familiar with that chipset, however I left before Orca became available. I may be biased but in my opinion Pixim had the best technology for WDR at that time but as it was new technology it did have some teething problems with how it worked in certain scenes and low light was never going to match CCD. Orca was supposed to address those areas and I was really looking forward to it. That being said I have never seen one as I left CCTV awhile back!

I've just read my post and my answer is a clear as mud! It is however about a clear as I can make it and I think it is right. It is no longer possible to read the number of pixels and guess a cameras resolution as the electronics now play a part. A 470TVL colour camera uses the same CCD as a 520TVL camera. Conventional PAL and NTSC CCD pixels numbers have been set in stone for as long as I can remember and there are two of them (well four due to PAL and NTSC). Here they are: HR NTSC Number of effective pixels: 768 (H) × 494 (V) approx. 380K pixels Total number of pixels: 811 (H) × 508 (V) approx. 410K pixels HR NTSC Number of effective pixels: 510 (H) × 492 (V) approx. 250K pixels Total number of pixels: 537 (H) × 505 (V) approx. 270K pixels HR PAL Number of effective pixels: 752 (H) × 582 (V) approx. 440K pixels Total number of pixels: 795 (H) × 596 (V) approx. 470K pixels MR PAL Number of effective pixels: 500 (H) × 582 (V) approx. 290K pixels Total number of pixels: 537 (H) × 597 (V) approx. 320K pixels It is probably worth noting that a HR colour CCD has the same number of pixels as a HR monochrome and there is no difference between 1/3" and 1/2", just bigger pixels. So CCD resolutions haven't changed but some colour cameras have moved from 470 to 520TVL. How did that happen? Something to do with the DSP. So now you can't use pixels to relate to TVL. It was a lot easier 5 years a go.

I don't see why a fujinon lens would help unless it is a video iris lens. The problem is the camera/lens is the lack of dynamic range of the camera and the way it is reacting to the highlights and so causing your lowlights to be under exposed. You can either try a wide dynamic camera such as the Panasonic suggested or one using the Pixim chipset or you can try and make the camera ignore the highlights. The second option will result in the highlights clipping but you will get better definition in the low lights. Features such as BLC and Pk/Av adjustment on a video iris lens could help. If you have advanced BLC you might be able to tell the camera to 'ignore' the bright areas. This would need a static scene, ie not on a PTZ and the truck always park in the same place. If you have a video iris lens you could set the pk/av pot to Av. This will weight the exposure towards the average light level and allow the peaks to over expose. Don't forget neither method will increase dynamic range, they just shift the exposure so you will lose the highlights but gain in the lowlights. It will always be a trade off, if you can't accept this you need to trade up to a more expensive camera.

If your camera have a switch on it labeled DC/Video then you can use your video iris lenses with the camera but you will need to get a DC lens plug. I'm surprised you didn't get one with either the camera or the lens. try calling your supplier and asking if they have any spares. You'll then need to wire it according to the manual. Red +12v, black ground and white is video or whatever they call it. Fyi here is some info on video iris lenses Video iris lenses use the same mechanics as DC iris lenses so there should be no low light advantage from identical lenses from the same manufacturer in DC or Video. They are supposed to be better as they come with 'intelligence'. However the installer needs to know this to get any advantage and most don't so it is wasted money for many. The intelligence is the Av/Pk adjustment, short for average / peak. How it works is the camera feed the lens power (red and black) and a copy of the video signal minus the syncs. You can hook it up to an oscilloscope and check if you want. The Av/Pk adjust ment changes the weighting between average light and peak whites. Turn it to pk and the lens shuts down more in response to spots of light, turn it to av and the lens will expose based on the average scene and allow spots to over expose. With a DC lens the av/pk is hard wired inside the camera to a setting determined by the manufacturer.

As suggested megapixel IP can achieve what you are after but you would have to take a drop in frame rate as a trade off or you need to search the web for three chip or three CCD and broadcast cameras. They will give you the resolution with analogue frame rates.

You need to come to the UK for affordable 1/2". We still use 1/2" quite widely for our city centre cameras. The JVC TKC-1380 that was once the system camera of choice in the UK was a 1/2" camera in PAL but a 1/3" camera in NTSC. I used to work for a company that was Sonys largest customer for CCDs in Europe, and we rarely bought 1/2" in EIA/NTSC and when we did it was for none US markets. The US market just didn't exist for the 1/2".

I'm just throwing in for Exview again. It is the most sensitive CCD on the block. Granted if you put it into a weak camera you won't get the best out of it. Panasonic do not use Sony CCD's, or they didn't when I tested cameras three years ago. The camera that Lolo Wolf has suggested looks exactly like one we had in the UK (I can't for the life of me remember the brand). I tested one of their low light cameras once and was very impressed, I thought it was going to be a novelty due to its small size but it had excellent low light performance. The fact this is a 1/2" camera makes me suspect it is by the same manufacturer as 1/2" used to be a mainly UK/Europe market. If that is the case I would recommend it. I'll try and remember the UK brand name.

I second Rory. The best low light performance without using slow shutter/frame integration is going to be from a monochrome Exview CCD.

I'm not sure what two filters you are referring to. All colour cameras should have two optical filters fitted in front of the imager. One is called the IR cut filter and the other is an optical low pass filter (OLPF). An IR camera doesn't have a filter. The two filters on a colour camera are usually put together in one block. It is the cyan piece of glass (actually crystal) you will see in front of the imager on colour cameras. The IR cut is there to stop IR light getting to the imager. That link is really good and gives lots of info but to put it simply an IR cut filter will stop wavelengths above about 750nm reaching the camera. Look at it as a pair of sunglasses for IR light. If these weren't fitted colour cameras would see IR and although this may sound like a good thing (better sensitivity) it has a major negative effect on colour reproduction. To understand you need to think about how we see colour, white light shines on a green wall, the wall absorbs all the light except the green wavelengths which bounce off the wall so we see a green wall. Now if the human eye could see IR we would see the green light plus IR light. The wall would no longer be green. For us in CCTV this becomes important for day/night cameras. For true colour you need the IR cut filter. For better sensitivity you don't want the filter, it's a pair of sunglasses remember. A good day/night will move the filter mechanically. A cheap day/night will just not have a filter, in which case the colours will be off, leaves are classic, the appear almost white. The OLPF is just weird.

There are some 360 degree cameras that computationally correct for fisheye lenses in real time, I know www.grandeye.com make one that is available through OEMs, I wouldn't use that to measure distances too accurately though but it shows how it could be done. They warp a fish eye into right angle perspectives for observational cctv not scientific measurements. When you start thinking about all the variables it gets a bit scary but if you have the know how to work out distances from a normal lens you may be able to calculate movement accurately even with a fish eye. As long as you fix the lens and the plane of the object you'd have to change your ratios depending on how far you are from the center line. Now I wouldn't know how how to start doing this by computer but I could draw some contour circles on the monitor that would give a rough indication of scale. The grandeye cam does it with a whacking hot GPU my way is cheaper.

I come from manufacturing, not installation so my knowledge is technical theory rather than installer real world experience so I may well be talking absolute rubbish but that's never stopped me. Take this with a dose of mmmm. You are seeing some of your cameras go out of focus during the day rather than at night and as you are aware this is arse about face to convention. We would expect to see a camera go out of focus at night as this is when the lens would normally be fully open and depth of field is at its smallest. I have two suggestions. 1. Could the cameras be set up incorrectly? Specifically electronic iris or auto exposure turned on with motorised iris lenses. I think I have seen this cause soft focus in bright light in the past as it usually causes a lens to open fully. 2. If you are using an IR pass filter I wonder if your cameras are seeing less light during the day than at night when your lamps are on? In which case you would have your worse depth of field during the day. If this is the case you should focus the camera during the day rather than at night. I don't think back focus is the issue. It may need adjusting to get you in focus but I don't see how it would cause the drift between night and day unless the shift is temperature related, so the mechanics move due to changes in temperature, you're not in some extreme location are you?.

Hi, That last bit could be misleading to some. It could be interpreted that an IR cut filter is a good thing to have if you want IR sensitivity when it is actually the opposite. IR cut filters stop IR, otherwise it would be an IR pass filter. An IR cut filter is a bad thing if you want your camera to be IR sensitive. All colour cameras (colour only or day night) should have an IR cut filter to ensure correct colour and grey scale reproduction. Most day night cameras mechanically remove the IR cut filter at low light to let IR pass.

The 1/3 and 1/4 refer to the size of the imager. Well it goes back to the diameters of the tubes used in very old cameras. A general rule of thumb is the larger the imager the more sensitive it is. Two identical CCD's in 1/4" and 1/3" have the same number of pixels so the pixels are bigger and hence more sensitive on the larger CCD.

Forgot to add that putting a filter between the CCD and lens will effect the back focus distance.

It is easy enough to fit a filter between the CCD and the lens on a black and white camera if you can get the parts. All colour cameras already have one fitted and as most manufacturers use the same mechanics for colour and black and white cameras you should be able to fit one in the same manner as they would on the colour models in the range. fyi the filter on a colour camera is called an OLPF and IR cut filter. The Optical Low Pass Ffilter gets rid of barbers pole (colour fringes) on edges and the IR cut filter stops IR getting to the CCD and effecting the colour reproduction.

Your theory sounds right. The 750nm filter, can you clarify how you use it for me.