Cooperman

The distance from camera to target issue, is relatively easy to grasp, but becomes technically more complex as conditions become more challenging. Under normal daylight conditions, cameras can quite conceivably be fitted with hyper telephoto optics (1000mm +) to pick up targets hundreds if not thousands of yards (or metres) away. The problems are 1) as distance increases so too does atmospheric obscuration (e.g. mist, fog, rain, smog etc.) although the effect of this can be significantly reduced by imaging at Infra Red frequencies in Black and White. Where it can become a serious problem is in locations where for example coastal fog can drift in, or dust storms can blow up in desert regions. 2) As the focal length of a lens increases, in general terms, the maximum available aperture (iris) reduces, so you need more light to achieve a decent image. 3) As the focal length increases, the 'depth of field' decreases so it becomes more difficult to maintain focus on a target, other than in a very small identification zone. 4) With any lens much over 100mm, even a slight wind loading on the camera housing, can result in a noticeable (if not nauseating) level of movement in the picture. 5) As focal length increases, the width of coverage decreases, so you have to make sure that targets are travelling pretty much along the axis of the lens field of view. Obviously at night, the longer the focal length (generally 160mm+) and therefore the smaller the maximum aperture, the greater the level of illumination needed to achieve a decent quality image. The way that Electronic Iris works, is exactly the same as an aperture priority automatic photographic camera. When you set the required aperture on the lens, the camera then automatically adjusts the shutter speed (usually between a range of 1/60 [NTSC] or 1/50 [PAL] up to perhaps 1/100,000 of a second, to ensure correct exposure. As the shutter speed increases, any target movement is then effectively 'frozen'. During the day, if it's bright and sunny you can expect exposures at perhaps 1/50,000th, and at night when it's illuminated to the correct level, perhaps 1/200th of a second. If you were to use an Auto Iris lens, the aperture would change automatically, but images would always be sampled at the basic rate of either 1/50th or 1/60th of a second, unless you manually selected a shutter speed, for example 1/200th second (not all cameras offer this option, and Auto Iris lenses are generally less efficient than Manual Iris in terms of optical performance, particularly with larger apertures at night). I hope this all makes sense

That's true; our home grown rodents only manage good old Wiels disease which causes blindness. You're far more likely to catch MRSA in a hospital, and that's just as a visitor!

They say in London, you're never more than 12 feet away from a rat; serves me right for having such close neighbours

Shame about the brochures rory, I was going to send you all my old 'archive' collection Hey frosted, I don't deal with any of the far east import companies so I can't make any recommendations. That said, I did have a chat with a guy who imports GSP equipment from Korea, and I was more than pleasantly impressed. No idea what the gear (or the company) is like, but if you check out their website, it's at http://www.ezCCTV.com I haven't looked myself yet, so don't shoot the messenger if it's a load of old you know what.

So hands up all those who are going to the IFSEC security show next week. I've nearly finished my training, just another three marathons and a thousand press ups and I should be about ready (in my dreams).

or, it could be a maddened meat muncher who'se pretending to be vegetarian

Hi sjmaye, You've had a lot of good advice from rory, so I'll just add a couple of suggestions. First off, without knowing the size or shape of your parking area, I'll have to be deliberately vague re: layout. You said that general lighting is good, and can be further upgraded if necessary. Where the vehicles enter the parking area, you want to make sure that they do so in a fairly narrow driveway. If at all possible, you also want them to slow up as they enter the 'recognition zone', so possibly a speed hump, possibly a turn in, either will bring the vehicle speed down to a more manageable level; in other words, basic vehicle management if practical. If you increase the night time illumination just in this small area using an illuminator offset to one side this will light the occupants without major glare from the windscreen; you would ideally want to locate the camera about 75' from the recognition zone, and if you use a 1/3" camera, go for a lens around the 50mm focal length (if the ground is level, try fitting around 12 - 15' high). Now, if you use Infra Red, you are limited to a quality Day / Night 'box' camera. If you use 'White' light, you can use a decent colour camera. My personal preference would be to go for a very good quality high resolution camera fitted with Electronic Iris, and use a manual iris lens, perhaps set to somewhere around f2.8 > f4. Camera fitted into a normal weatherproof housing. This is 'unconventional' by most peoples standards, but the idea is that where the EI controls exposure during daylight hours, the high shutter speed (perhaps 1/50,000 in bright sunlight) will effectively freeze each image captured (30 frames / second in the States) so there is no blurring in the recording. If you use an Auto Iris lens, you cannot exploit this advantage. In the past, this technique has worked well up to quite high vehicle speeds, but you must make sure you have enough illumination at night (remember you are only lighting a relatively small area) - you should still be achieving perhaps 1/100 > 1/200th shutter exposure if you get the lighting right. For rear number plate capture, exactly the same technique, but perhaps locate the camera slightly closer, maybe around 60 feet (I don't know the size of US plates compared to UK plates, so you may need to experiment a bit. When setting up cameras to cover the parking area, ideally you do not want them located in the same place; crossing over / in opposition would be preferable. Try and keep the angles narrow and view at distance, rather than wide angles close to. If you roughly sketch out the area on paper (to scale), mark up possible camera locations and then cut up pieces of paper to match the lens angles, you can move them around to see how best to cover the area, with the least number of cameras. The principles are exactly the same as we used to use for plate recognition with old B/W 'tubed' cameras, but there wasn't the advantage of Electronic Iris in those days!

Bacardi!!! ... now why didn't I think of that (Mrs. C's favourite tipple... sorry, drink). Had to blow out the 2nd visit today s**t happens Not sure about the passing Manchester bit rory, if I went to Birmingham from London via Manchester, I'd have to set out the week before As it is, driving to the show was a five hour round trip, so I suppose at least that's one thing I won't be missing today. Still all the more time to read through the brochures, brochures ... so many brochures! Anyone else managed to get there, and what did you think?

One trick you can try for protecting screw heads; if the screws are removable, fit a split plastic screw cap, and before you click the cover on, coat the entire screw head with 'Silicone Grease' (plumbers use it for sealing water components). It's messy stuff to work with, but it can make a big difference. Without it, as Data Ave rightly says, salt will eat away at anything metal.

A little clue to help identify the meat thief ..... it's probably not the vegetarian

A member of this forum moonlighting as a web designer ... who is that masked man???? ... elementary my dear Watson

Went to IFSEC yesterday, Don't know what hurts more today, my head or my feet! Only managed to get round about fifty stands so far, so it looks like I might have to go back again tomorrow (still 650+ to go!!!). I stopped counting DVR's when it went past 150. Strange how they all begin to look the same after a while, apart from the ones built into 15" LCD monitors. Seen enough 'bullets' to start a price war Can't decide .... beer or aspirin ....

hey frosted, I hear there's some hotel rooms available in Carlisle - perhaps not quite close enough?

I wouldn't disagree with that DataAve

There may be a big pond between us, but it all sounds depressingly familier

The iris mode 'ESC' and Electronic Shutter Speed : NTSC AUTO would confirm that it's Electronic Iris, as opposed to Electronic Shutter which may simply be the option of manually setting a fixed shutter speed. I'm sure I've come across an AI lens on a PCB camera not that long ago, but I can't for the life of me remember where I've seen it. Bit late to be looking tonight, but I'll have a trawl through my files over the next day or so. If I find anything, I'll let you know.

For what it's worth, good on yer dipshwich for having a go at something that many would not. Plexiglass, polycarbonate (and to a much lessor degree Acrylic) are all readily used as housing windows where impact resistance is a primary requirement. The down side is that although the material is optically acceptable for the job, it does tend to be far less scratch resistant than glass over a period of time; but then if it's cheap enough, you just throw it away and fit a new one. Some years back, I had to build some very heavy duty camera housings using 6" sewer pipe, which were then submerged in thirty feet of water. As it was a temporary project, the cameras had to be permanently sealed into the housings (glue welded), and then cut out afterwards using a hand saw. As dipshwich admirably demonstrated, if you are inclined, you can do quite a bit yourself and it needn't cost a fortune.

Just a couple of quick points on the video cable issue, The improvement on signal attenuation (if you like, how much it degrades the video signal with distance), is not hugely better with RG 6 than RG 59B/U. RG 11 is almost twice as efficient as RG 59, and so in general terms, you can run roughly twice the distance to achieve the same degree of degredation. If monochrome cameras are being used, the furthest run I've ever tested was about 1500' on RG 59B/U and the attenuation certainly produced significant degredation in the received signal. The picture was more than adequate for the clients purposes, but overall it was a very 'soft' image. It is important to remember that as a cable run gets longer, it is the chrominance (colour) portion of the signal which is lost, long before the luminance (monochrome) begins to degrade. Generally, most manufacturers will rate RG 59B/U as ideal for both colour and mono cameras up to around 200 metres (600+ feet). Mind you, there can be quite a varience in quality between cables sourced from different manufacturers, so any rough guide has to be taken as such until tested in the field.

kaysadeya, ditto rory's last posting. Where the spec shows an AES (Automatic Electronic Shutter or EI Electronic Iris) range of shutter speeds from 1/60th > 1/100,000th of a second, they are not designed to accept auto iris lenses. If you fit a good quality manual iris lens on to the 'CS' mount board camera, provided you have sufficient illumination for low light use, you can set the aperture (iris) to perhaps f2.8, and the variable shutter will take care of the exposure under all lighting conditions. Using this arrangement, you'll have very crisp images of moving objects during daylight hours.

So frosted, you're off to IFSEC! Good luck mate!! If you have time, it's worth doing a bit of homework before you go - have a look at the show website for the exhibitors list - http://www.ifsec.co.uk Try and short list perhaps ten 'must see' manufacturers, and then do your best not to get too confused or blinded by science. There's over 700 exhibitors and I can't tell you how much I'm looking forward to it ... honest, I really can't tell you You've had loads of useful info from the other guys. Just to quickly clarify a couple of points though; if you are watching staff activities, your client will need to register the CCTV system under the Data Protection Act and it will need to be compliant with the legislation. Also the overt / covert argument could pretty much fill a book on its own. Generally speaking, in the UK overt cameras do have a measurable deterrent effect, but not if the target is 'out of their head' on drink or drugs. If there is an ongoing problem with damage / vandalism, the golden rule is covert first to achieve a result, then you can always go overt later on. It rarely if ever works the other way around. So, who else is off to the show .....? Come to think of it, probably not the right place for that question (best to start another thread, eh).

Thanks for the review kaysadeya, Would you consider scoring marks out of ten for various features? It might be useful for anyone wanting to do a quick comparison if in the future, others do the same. Just a thought.

Nice line in irony , baywatch and well done rory! Now all you have to do is test them all if you have any time to spare!!

Hey baywatch, The VIP lounge (stand V10) looks good to me - I suppose I'll have to wave to you from the outside

Just discovered a new CCTV website - well worth a look! http://www.doktorjon.co.uk

Rory, you've got to stop working all day in the sun, it can drive a man mad!