Cooperman

WookieBoy, The 10 metre rule is about planning legislation, so the Police would in almost all cases be totally unaware of it. In practice, if material were submitted to court it would be up to the judge on the day to decide whether it was admissable, even if it breached the legislation (untested waters ). Is there any way you could mount the camera away from your property (perhaps covert) then it would be outside the scope of the law. As I mentioned in my previous post, it is theoretically possible to nobble a digital recording (with or without a range of different tape marking techniques), but at the moment, it is simply regarded as a sensible safeguard to have some mechanism in place that would present a reasonable assurance that a recording hadn't been tampered with. kensplace, Agreed it is a very silly rule, but then we have loads of those here in the U.K. (makes you proud to know we're really good at something!). Incidentally, brave of you to post the link; the last time I referred to that site, I had to do a quick finger count as I nearly lost all the digitals off my left hand

Worth mentioning kensplace, that if you use a HOT filament bulb with a plastic filter, it may well melt There is a standard perspex material that can be used for Infra Red work (if you just want to have a play around), but commercial illuminators normally use either 'dyed in the mass' glass or 'dichroic' filters. Incidentally, there used to be 50W Low Voltage Halogen bulbs that had a special gold coating on the reflector - if I remember correctly, the idea was to direct more light forwards, and more heat backwards, although from what I could tell, they simply diverted more cash into the suppliers bank account

Hi jisaacmagee, I've just read through this post again for the third time, and quite honestly, I need a stiff drink What should be a fairly simple concept to explain in perhaps a dozen lines, has been given what can best be described as a thoroughly confusing, and in places quite inaccurate and misleading work over, which had me scratching my head trying to work out what was being explained, so goodness knows what some of the less experienced guys would have made of it No disrespect intended J., but with your broad practical experience, and given some of your previous excellent postings, I'm sure you could have explained this concept far better, and in a way that could be easily understood by all. I'm not going to go through this epic piece line by line, but for what it's worth, here are just a few of the points which perhaps need clarifying:- 1) Two fields combined into a single frame are described as being 2:1 interlace... not interface. 2) You don't just use higher resolution cameras outside - the golden rule is to use the highest resolution camera that can be afforded, whatever the application. 3) Suggesting that the maximum number of lines in the scanning system ( i.e. 525 EIAJ / NTSC & 625 CCIR / PAL / SECAM ) equates to vertical resolution is patently wrong. The scanning system will only limit the maximum available vertical resolution, and in most cases, the average camera VR is nearer to 400 lines. 4) I'm suddenly getting a serious case of deja vu; I'm sure we've been through this before 5) Image resolution, or to be more accurate camera resolutions, are often subject to many types of degradation which have absolutely nothing to do with the principles of system engineering; for example, smoke in bars, heavy rain, fog, dirt on housing windows etc. 6) In practice, the resolution chain is only as strong as its weakest link, and based on the sequence in the article, it should be ... camera, lens, illumination, transmission, recorder, monitor, and whatever else you want to throw in to the circuit. Actually, come to think of it, illumination was never even mentioned, and low light causing camera AGC circuits to work hard, with increased noise on the image, is a sure fire recipe for reducing resolution. 7) Suggesting that "we can loose resolution or quality of image using longer than usual lenses" is quite misleading. In general terms, telephoto lenses are far better corrected optically than standard or wide angles, so in most cases, are capable of much better resolutions than their shorter cousins. This is particularly true of longer lenses, which are normally designed for use on larger formats. It is also true however, that where longer lenses are used to observe over greater distances, then atmospheric conditions can serve to reduce the perceived quality and resolution. I'm way too tired tonight to cope with much more, but suffice to say, I agree with much that kensplace has already said. If you capture a cracking good image on an average camera, it will always beat a poorly configured high resolution camera. Personally, I never use anything but high res. for my own work, but that's not to say that I don't on occassions have to get the best out of some clients poorly designed systems, when they're not prepared to spend any serious money on improving it. Life is way too short to be making things overly complicated, and difficult for many people to understand Maybe I'm just getting a bit picky as I get older, so apologies if this sounds a bit like a rant, but sometimes keeping things simple is far more worthy of respect, than when some experts just simply try too hard to prove how clever they are.

The bottom line sodagar is probably about money rather than technical performance. If you used a very expensive brand new CCTV monitor built perhaps 10 years ago and compared the overall picture quality to a much cheaper modern quality branded television, I wouldn't mind betting the modern TV would probably look better overall. That said, a number of 'industrial' monitors are built using common components that are also used in some domestic televisions. If you are looking to save on cost, and you've seen or know of a very good television with excellent picture quality, then it may well do what you want. I should perhaps mention that some TV's and indeed some monitors can be less suitable for playing back recordings (particularly analog or time lapse), but nowadays this shouldn't really be a major concern.

Hi peshaw and welcome, The "T" factor of a lens refers specifically to it's ability to transmit light through the optics. Very few manufacturers use this measure (it's probably far too honest for most to cope with ), but prefer to quote the 'f' figure for the maximum aperture of the lens. Whilst it is generally accepted that the smaller the 'f' number , the larger the aperture and therefore the more light should be passing through it, in practice the size of the aperture is simply an indication of expected performance, as it does not allow for the quality of the optics, lens coatings or efficiency of the optical design.

It's also worth bearing in mind that the wider the aperture (i.e. the smaller the 'f' stop), then the lower the lens resolution will be. This will be particularly noticeable in terms of 'edge' resolution.

cailun, It is a question really related to the application. If you were watching a small area, with reasonable lighting at night, then a camera fitted with a manual iris lens (stopped down a couple of stops), and with the Electronic Iris switched on, would almost certainly outperform the same camera fitted with an Auto Iris lens, working under identical conditions. By closing the iris a couple of stops, it allows the camera to operate in the brightest of daylight conditions (maximum shutter speed), or under night lit conditions (minimum shutter speed). Where a camera is required to produce an image from very low light through to intense sunlit conditions, then Auto Iris would be the preferred option.

It certainly should be Thomas, but .... how many lens manufacturers can you think of that use the 'T' factor to express their products light gathering capabilities. In an ideal world, it would be very useful if all companies used a standardised measure, but as they don't, we're really stuck with a well proven concept - which is very roughly, don't accept as accurate anything that is written down on a specification sheet, until you've had a chance to prove it for yourself

debennett2, Before you start spending money on lenses, there is one old trick you can try just to see if the cameras are working. If you can get hold of a piece of cooking foil ( I think you'd probably call it aluminum foil ) and smooth it out, then cover the front of the camera with it, make a tiny pinhole right in the centre (sorry, center!) of the lens mount and then set up your power supply and video cables to test if it's working. You should be able to produce enough of an image to see if the cameras are working electronically, but you certainly won't be able to capture license plates at 100 yards The Sanyo VCC 3974 is the 24v version of the '3972' which I used to use by the bucket load. It's a good solid little camera, and although it's a few years old now, it should produce good quality images with the right lens fitted. There is a large range of optics available, and so choosing the correct lens for the job, will depend specifically on what you want to do with the cameras. Do some initial basic tests first, and then post back. Incidentally before I forget, if you have a small phillips cross head screwdriver, remove the side panel from the '3974' (I can't remember which one - make sure the camera is NOT powered up when you do this!), and turn on the small switch which is marked "EI". This will enable the electronic iris function, which will correctly expose the image for your given lighting conditions.

Your question initially relates to the maximum aperture of the lens and so should (in theory) provide an indication as to the light gathering capability of each optic; i.e. smaller number = bigger aperture = more light passing through. So whereas you might expect that the f1.2 lens will work much better in low light conditions than an f2, in practice, the quality of the glass components (known as elements), the lens coatings and the basic optical design, will affect the eventual quality of the image. Before I forget, you need to check that the lenses (particularly the f1.2) are 'C' mount so that they will work on your C mount camera. If they are 'CS' mount, they will screw on to the camera, but you won't be able to focus an image. As regards auto iris lenses, in general terms, the graduated 'ND' neutral density filter which is fitted into an auto iris lens, serves to not only degrade the image, but also force the aperture to a wider setting, which in itself reduces the optical performance of the lens. That's really a rather brief answer, so if you want me to bore you senseless with an even more detailed explanation, you only have to ask!! BTW sodagar, welcome to the forum

Hi sodagar, Although you've posted some fairly straightforward questions, unfortunately there aren't really straightforward answers. As regards using a high res. colour camera with a 4mm lens, to some degree the results will depend on the build quality of the camera, the lighting, the quality of the lens, and of course your transmission system. If you have a top quality camera fitted with a superb optic under ideal lighting conditions, the image of a persons face displayed on a half decent monitor might just about be acceptable for recognition at 12 - 18 feet from the camera. Ideally you'd be looking for a face to occupy perhaps 1/6th of the screen height, in which case your target would need to be around 6' from the camera. If at all possible, try and use a narrower lens (maybe an 8mm or longer, preferably 1/2" format or larger) at a greater distance, which should give you a much better quality image. The comparison of a 21" TV and a 21" monitor will vary from one model to another. Depending on how mission critical your application is, and how much of a hammering you intend the display unit to receive. it's quite possible that the TV will fit the bill, although it must be stressed that it is not designed to work at the same level as an industrial monitor. The issue of compression is another less than simple topic. In simplistic terms, MPEG 4 / H264 will produce smaller image files so will allow more images on a given disc space, but other formats such as MPEG 2 and Wavelet will produce less compressed images, and will therefore require more space for the same record period. In practice, the settings on an individual DVR will significantly affect the efficiency and quality of the eventual recorded images. As regards the DSL calculation, whilst our systems are significantly different from what's available in your neck of the woods, you'd best calculate your requirements, provided you know what the average image file size is, in relation to the number of cameras connected and the number of images per second. Hopefully other guys will perhaps be able to give you some more specific figures, based on example standard equipment and systems available where you are.

Went past a garage (gas station) today with a price equivalent to US $ 8.24...... still goin up

I have used Composite : VGA adaptors in the past, although for most practical situations, the quality wasn't anything to get terribly excited about.

The various techniques used for authenticating DVR recordings are vitally important in themselves, but having said that, there is (in theory at least) a relatively simple way to fabricate 'evidence' which is authenticated as "original". For obvious reasons, I'm not about to publish that on the forum.

Without wishing to state the obvious, if you want to test the resolution of a camera using a test chart, you have to make sure that a quality lens is used, and in particular, that the lens is capable of resolving more lines than the cameras imager. If a camera's resolution is visually tested on a high resolution monitor, it is then fairly straightforward to make a test recording (from that same camera / lens combination) and see what quality results are achieved on playback.

Just so you're aware WB, If you are installing 8 cameras outside, you can't have more than 4 on one side of a building, and they must each be at least 10 metres apart. Any less and they would be classed as unlawful, and any evidence you later capture on your DVR may (in theory) not be admissable as evidence. As to choices for DVR's, there are literally hundreds on the market, and many of those discussed on the forum, are not available in the U.K.. Your choice will very much depend on how much you are prepared to spend. If you're looking at the 'budget' end of the market, quality and reliability may not be at the level you'd ideally like.

I'm surprised the police didn't ask your dobie for a statement You have to take all necessary precautions, and whilst slowing down a break in is an obvious and conventional technique, it doesn't always work so well in rural locations; simply because there isn't the density of neighbours to react to the attempted break in. That and police response times are much longer out in the sticks. It is a fact that rural crime is taking off simply because there are so many soft targets. Town Centre camera schemes have pushed the problems further out, and so the days of leaving a back door unlocked, are well and truly gone forever. Get all your physical security sorted first, and then plan your CCTV very carefully.

If you think that's bad, our government department, The Home Office have 'lost' loads of murderers and sex offenders who have been released back into society after very brief sentences, and are now desperately trying to track them down. Now you know why we have so many cameras in the 'hood' (estimated at 4.25 million and counting!)

WookiBoy, There's lots of useful information and advice from freeflyer, but there are a few points which I would have a slightly alternative view about. First off, if your camera system is installed at a residential location (i.e. not commercial), then there is no requirement to comply with the Data Protection Act. All domestic installs are specifically exempt from the Act (as indeed are many lower end commercial installs). Planning legislation, and specifically 'Permitted Development' rules are very exact about what is acceptable. If you breach this law, then it is theoretically possible that any evidence obtained may be rejected as having been obtained unlawfully. I would tend to suggest you look at a standalone DVR rather than a PC based system, simply on the basis of 'ease of use'. Getting an experienced CCTV engineer in to advise you is better than nothing, but in my experience, really good ones are very few and far between. There are no specific rules and regs regarding "identification of individuals" just some general guidelines which by modern standards are actually not as informative as they should be. As an example, if it was stated that a target needed to fill 50% of the screen height to be acceptable for identification purposes, it does not take account of the camera / lens combination and recording system. If you use a standard res. camera with a rubbish lens and record at low resolution, the target can be 50% of screen height and you still can't work out if it's male or female. Go for 10% screen height with a multi megapixel camera, and it's a whole different ball game. If you've previously installed cameras for your own work, you can almost certainly DIY, albeit you may need a few pointers to get you started.

cro70 The issue of setting up a cameras back focus is very straightforward, and is certainly something that has come up a number of times before on the forum. For a motorised zoom lens, as rapid has already suggested, the first thing to do is to open the lens iris. If it is a motorised iris, then you can hopefully do that with the controller. If it is an 'Auto Iris', your options are either to wait for very low light conditions (so the iris opens fully on its own), or use a dense neutral density filter or equivalent, to reduce the amount of light passing through the lens, and so force the iris to open. Using the lens controller, set the Zoom to maximum telephoto, the Focus to Far, point the camera at an object in the far distance (maybe a tree on the horizon) and then adjust the back focus until the image becomes sharp on screen. If you are intending to use Infra Red illumination, you may need to adjust the back focus slightly to allow the extra focus adjustment required to compensate for 'focus shift', which is present on most lenses being used at higher IR frequencies. If you use an IR illuminator with a removable filter, you can easily hold that over the front of the lens, and then make any adjustment to focus under 'IR conditions'.

Hi WookieBoy and welcome, Sorry to hear about your unwelcome visit; good to know from our esteemed leader that crime is going down - so at least all us Brits will be able to sleep better at night You probably know this anyway, but before you start replacing all the nicked gear, make sure you do a thorough review of your security, and if you have a budget available, think about installing one or two covert cameras. It's not at all unusual to hear of premises being robbed, the gear being replaced, and then the culprits (I could have used another word there!), decide to pay another visit (they always seem to know when gear is likely to be replaced) and certainly make sure that you don't leave any replacement product packaging lying around; it's almost as bad as hanging up a sign saying 'come and do me'.

Nineteen and a bit months of operation in the last two years, and they're a bit poorly; it's not exactly impressive! I have certainly seen operational problems where monitors have been used in a high temperature environment, e.g. stacked monitors, poor ventilation, no air-con etc. which can rapidly degrade components on the PCB's. Most decent monitors have a sub brightness pot on the main circuit board, so whilst a degree of circuit wear can appear to present a significantly reduced brightness adjustment on the front panel, by tweaking up the 'Sub Brightness' you can often recover most if not all of the previous level of Brightness control. It might be worth finding out if they are internally bench adjustable to ofset the wear and tear.

Hi MgJ, My previous suggestion was to drive the P/T motors directly with a low voltage supply, rather than using the data driven controller. That would confirm whether the problem is in some way connected to the 'Data' circuit, rather than the driving circuit (e.g. possibly the motors themselves). Most electric motors (particularly DC) are electromagnetically noisy, so when they operate, they can spit out airborne (and cable borne) interference. To counteract the problem, manufacturers generally fit electronic components, usually either an electrolytic capacitor, or an R/C suppressor, which is a component that contains both a resistor ® and a capacitor © wired togethor. The effect is to gently filter or smother the interference. If you have not been required to work with electronic components in the past, it would be sensible to get some advice from a local supplier, particularly as fitting the wrong value components can potentially create other problems. A VDA is simply a Video Distribution Amplifier. It's purpose is to take a standard composite video signal, then internally boost (amplify) it and split the signal to a number of outputs (usually between 3 > 10). The idea behind the suggestion was to 'condition' the video input so that you would know that a good 1v P-P signal is being provided on one of the outputs. I just noticed in your original post that you mentioned having received a lightning strike in the past. That would increasingly suggest to me that something has broken down at component or motor level. It's a shame you don't have access to an oscilloscope for fault finding, but then that's a whole different ball game

To all the forum members on the other side of the pond, have yourselves a great 4th July!! Regards Cooperman

Sorted! Thanks for that larry