Stanislav

The SENSORS in both cheap and expensive cameras may be the same, and thus the same price... There is a contradiction in this sentence "cheap and expensive cameras " vs " thus the same price" May be. It depends what do you imply on the"actual performance ". But I speak here not about indefinite " actual performance". I speak about real defined parameter - SENSITIVITY (same exposure, same resolution, same signal/noise ratio, same lens aperture). This sensitivity will be the same with the same sensor. Sorry.. I must to remind you once again: I speak here not about indefinite " image quality ". I speak about real defined parameter - SENSITIVITY (same exposure, same resolution, same signal/noise ratio, same lens aperture). Please see Page 9 Camera sensitivity and Page 10 Parameters, limiting image quality at defining sensitivity.

I can look at the sun and tell you what time it is, how's that? It is really Great!

where does all the collection of information start for any camera ??? Lens Lens aperture (F-number) determines amount of light passing through it and thus only the aperture have influence on sensitivity. For example, there are very expensive varifocal megapixel lens with F1.4 and low cost lens with fixed focal length and F1.2. The F1.2 lens will provide better sensitivity in 1.36 times. I also compared lens resolution and come to a conclusion that cheap fixed lens is better. But we speak here not about resolution .

in cctv Price (consruction cost of camera) is a big factor .... you have to put price of each component together. cheap ....... bad lens (plastic) good quality glass optical lens Certainly these factors are important in CCTV as well as the price. But we speak here about sensitivity. So the brand name, lens material (with the same aperture), box material, inputs, outputs etc have no influence on camera sensitivity, but have influence on camera price.

I would like to divide experience + reputation and real knowledge. As I wrote above "Many designers consider lighting and sensitivity very complicated field which can't be understood. In spite of this fact the designers do their work ". These designers have good reputation and good experience but lack of knowledge of lighting and sensitivity. Also the price is generally out of this question. The sensitivity is determined by used image sensor which is not only component of camera price. Cheap and expensive cameras (with the same sensor type) have really close sensitivity in spite of difference in price and difference in values in specifications.

It's not just that... the root of the problem is, there IS NO defined standard for measuring and publishing camera light sensitivity specs in the CCTV industry. Fiona and Stanislav could have the best, fairest, most accurate test methods in the world, but there's nothing that forces the camera makers to use those tests, or any tests. As it stands, a camera that claims ".01 lux" could be referring to the level at which it gets a usable image... or the level at which the sensor gets measurable output. There's no standards body that requires them to say what kind of output they're looking at. The problem is deeper. Actually, there are several standards and it is possible to develop any necessary standard, but the CCTV industry doesn't need standards. This is a commerce problem. And problem of CCTV designers knowledge. The most of buyers of cameras look only on sensitivity value and don't want to know more. While cameras with 0.00001lx in spec are sold better than cameras with 0.04lx in spec, the 0.0001lx will be written in camera's spec. That forces honest manufacturers to resort to tricks too. In other case they would lose money. It is impossible to explain to all customers what is the sensitivity and why its value in their spec is lower in 10 times when the customers look only on LUX value. But the honest manufacturers can't lie directly. Therefore parameters in spec of honest manufacturers are right in general, but only skilled engineer can understand this. For example, sensitivity is corresponds to long exposure time or to low resolution. Thus we again come to the designer's knowledge. I don't want to force manufacturers, I just offer tools and articles for designers which can help them to increase their knowledge.

I developed real testing procedure. It is described step by step here. This procedure has been published in 2007 with VideoCAD6 and corrected in 2011. Using this procedure I tested cameras and got these results. These results fulfill the criteria: 1. Signal/noise ratio - 17dB 2. IRE - is measured while testing. It depends on max AGC gain of the camera on test. See Page 10 "Parameters, limiting image quality at defining sensitivity" for details. 3. Lens aperture - F1.2 4. Light source - tungsten halogen lamp with nominal supply voltage 5. Exposure time - 20ms 6. Resolution was not checked in this sensitivity testing. You can find some real tested models in the Table of Camera Models in VideoCAD demo. But these models are not widely known. My supplier offered me these models at the moment of testing (in 2007). Actually only one model in my test gave result equal to spec value - PELCO MC3710H-7X. Its sensitivity was 0.07 lx at 40IRE with the lens F1.2. The camera has 1/3" SONY Super HAD™ CCD

Not in all cases "megapixel" lens is better. Standard fixed focal length lenses can have really better resolution than Varifocal megapixel ones.

This is the problem, though: low-grade manufacturers often DON'T BOTHER TESTING. They DO use the on-paper, theoretical specs... or publish specs "inspired by" other similar cameras. IR ranges are calculated based simply on the number of LEDs they can cram in, with no accounting for how well they're aimed, how even the output is of the individual LEDs, how steady the drive current is (20%-tolerance current-limiting resistors can cause a lot of variance), and so on. I wrote the same above: Right tests are accurate. But parameters in the specifications weren't obtained from real tests. Many manufacturers don't test their cameras! I have in my customers several camera manufacturers. They really don't know how to test cameras They don't need to test them. These parameters became more marketing than technic. Therefore we need to fix all important conditions: 1. Signal/noise ratio 2. IRE 3. Lens aperture 4. Light source 5. Exposure time 6. ?Resolution 7. We should disable noise reduction when testing.

Yes, 1/3" CCD has smaller pixels therefore it collects less number of photons, therefore its sensitivity must be less. However there are other factors: 1.Smaller pixels can have less "noise that is inherent in the CCD ", less number of noise electrons (it is my supposition). Actually the sensitivity is limited by the number of noise electrons and the number of active photons. 2.All calculation in this article made for "source of white light with uniform energy distribution ". For a source with maximum in IR range ( tungsten halogen lamp ) the sensitivity will be higher, as the greater part of "valid" photons will be out of visible range. 3.Sensitivity for 17dB SNR will be higher than for 24dB SNR. In my own tests I got the practical results for 1/3" ССD and a tungsten halogen lamp: 1. Sensitivity of black-white cameras with high resolution CCD image sensors (752x582 effective pixels) 1.3" IT CCD, Sony Super HAD CCD is 0.06-0.15lx at signal/noise ratio =17dB, lens aperture F1.2. 2. Sensitivity of black-white cameras with high resolution image sensor (752x582 effective pixels) 1.3" Sony ExView HAD CCD is 0.04lx at signal/noise ratio =17dB, lens aperture F1.2. Please see other results of my tests here

Today I have contacted with Nikolai Uvarov and he just gave us his great article in English. Nikolai Uvarov,"The secret of higher sensitivity CCTV cameras", "CCTV focus" Issue 23 - May/June 2003. It is really interesting reading if you are interested in the physics.

I know, Rory

Useful tests are done out in the field. OK, it is your opinion.

And that is why those tests are inaccurate for real world apps. Right tests are accurate. But parameters in the specifications weren't obtained from real tests. Many manufacturers don't test their cameras! I have in my customers several camera manufacturers. They really don't know how to test cameras They don't need to test them. These parameters became more marketing than technic.

I didn't write so. Please be accurate in the dispute. I assert that all cameras in my tests with the same sensors and the same lenses with the same shutter speed produce images with the same threshold signal/noise ratio (17dB in my test) at approx the same illumination. Actually the type of image sensor is much more informative than sensitivity value in the spec.

Testing IR cameras indoors is next to useless (or any low light camera). You need a long wide area to test to really put the camera to task. I test in my car park, 70x60', and also test in a small area, and in the garage, and on a long narrow balcony - the difference between the car park and the other areas is like night and day with how the cameras perform, most suck in the car park, it really tells what camera is the better camera. To test cameras there is no other way but out in the field, thats one reason why the specs for cameras are so incorrect, most manufacturers themselves dont even go outside to test. Please try explain your reasons scientifically. You are really mistaken here, Rory. All professional tests are performed on stands, not in outdoor field. All camera parameters can be measured on laboratory stand.

If these cameras have the same sensor and the same lens, same exposure time and these cameras have no problems, their sensitivity must be the same. I carefully tested tens of cameras of different price and I assert that the Image sensor and lens have much more influense on real sensitivity than camera price. Actually the price have no influence on the sensitivity . But may be you used cheap imitation and your $80 camera has no really Sony Super HAD CCD? Or it has some problems? Other question is that threshold parameter did you accept for estimation of sensitivity? It must be Signal/Noise ratio, NO IRE! If you use IRE, you fall into a trap. IRE depends on maximal AGC gain, which can be different. I highly recommend my article to understand this, see Page 10 "Parameters, limiting image quality at defining sensitivity". I don't deny real testing. Moreover I developed procedures and software for real testing. But we can't test all possible combinations of lens aperture, exposure time, light sources etc. We can test only one mode then calculate other situation using know physics laws. DVR can be examined too, but it is out of question of camera sensitivity.

the only way to know the sensitivity of a camera is to test it out, specs for cameras are all over the place, you get some that claim 100' IR when it only does 30', one that claims 80' Ir when it only does 40'. Bottom line is one cant rely 100% on specs to tell them how a camera will perform. One needs to actually get out in the field and test them. You need not " get out in the field " to test them. Just make a simple stand in your room. Actually, you can make some simple tests even without my software. But understanding is needed in any case.

Generally I agree with you, Soundy. But why do you think that the factors you mentioned can't be taken into account in calculation and modeling? Please see my article above. These factors are taken into account: Light spectrum and camera spectral sensitivity, Lens aperture, Shutter speed, AGC (Electronic gain processing ?), Gamma, Reading Noise and Photon Noise (in internal camera parametric model). Real cameras have no such problems as a rule. In any case these factors are taken into account while practical measuring. I don't agree. The Sensitivity in 99% is determined by the Lens and the Sensor (with fixed exposure). Other processing can't increase sensitivity, it can improve some parameters (for example signal/noise ratio) at the expense of making worse other parameters (for example -resolution). I don't like cameras with complicated processing because their behaviour is unpredictable. I have to examine such cameras more carefully Many "realtime image processing" are advertising slogans only.

I agree with David Elberbaum, we can't use values of sensitivity from specifications. The best way is understanding what is the sensitivity and be able to measure sensitivity using open techniques. Or you can rely on your practical experience only and avoid any calculations in this field. Many designers consider lighting and sensitivity very complicated field which can't be understood. In spite of this fact the designers do their work .

In my article I tried to explain only basic things of lighting and sensitivity which are useful in CCTV design. As a rule the light is considered as a superposition of wavelengths(spectrum) when we consider Spectral distribution and Spectral sensitivity. In light engineering and in CCTV engineering it is sufficient to consider light as a waves. But the Light must be considered as a number of photons when we calculate noise of videosensors. If you are really interested in this, I recommend excellent article Nikolai Uvarov,"The secret of higher sensitivity CCTV cameras", "CCTV focus" Issue 23 - May/June 2003. It is really interesting reading if you are interested in the Physics. See also David Elberbaum,"Unravel and undo the unreal CCTV camera specifications", "CCTV focus" Issue 37 - 2006 Quite the contrary. Because of the wrong parameters in specification, who really want to investigate these questions must look into the theory and be able to measure camera sensitivity independently. It is not difficult. Here are the technique

It is almost impossible between specifications of different manufacturers. Not quite. 40dB is the maximal AGC value. It means that the signal from the videosensor can be amplified with the gain factor adjusted automatically in the range of 40dB to keep optimal image contrast. Yes but in case of the Gamma factor =1 and AGC is OFF. In real cameras with Gamma=0.45 and AGC =ON this dependence is more complicated. It is not simple. Please see my article Illumination and camera sensitivity in CCTV. I hope it will be helpful.

It seems like a problem of cheap color "infrared" camera, i.e. color camera without IR cut filter. If scene of such cameras is illuminated by a light source with high IR component (incandescent lamp) then colors of such cameras will be distorted. But in case of using light source without IR component (luminescent lamp, discharge lamp, etc), the colors should be good. If your warehouse is illuminated by incandescent lamps, to avoid such color distortion don't use color camera without IR cut filter. Use color cameras with IR cut filter or (if you use also IR illumination) - use True Day/Night or Black/White cameras. Or accept such color distortions.

May be you don't believe me , but our problem is opposite - frost. When a camera is working, it produces enough heat for working even in strong frost. But the same camera can't start after non working period in frost. Actually all electric power consumed by camera (0.15A*12V=1.8Watt) is transformed to heat except of electric power of output videosignal in cable (no more than 0.01Watt). There is no way for output energy from camera except the heat and the videosignal. Use a digital multimeter with thermopair sensor to measure the temperature inside camera box after working in several hours. Then compare it with environment temperature. It can be interesting.

Please give a link to information about your encoder. As a rule relay connection is simple, but depends of type of outputs.