Cooperman

"odd goings on" Basil, how could such a thing be possible? I suppose I should have spotted the clue to the lens being an ultra wide - that's why the camera casing is showing in the upper corners of the picture. On the very odd occasions I've used 2.9mm barrel lenses in the past, I've actually found them to be surprisingly good, but I'm guessing the £ 10 jobby is possibly not a terribly good pedigree, which is why the resolution is dropping off quite dramatically towards the edges. If the IR illuminator is used to 'spot illuminate' the shadow area, you may actually find that the results are quite acceptable for your purpose. The chances are you may have something of a 'hotspot' in the picture, but you won't know that for sure until you test it. One thing you could try is to get hold of a basic diffuser, perhaps a small piece of frosted glass from a local merchant (temporarily tape it in place over the front of the IR using electrical tape), and see what kind of effect you get locating the illuminator under the porch (bottom left of picture) pointing towards the back of the red car. You've got reflective gravel and plenty of foliage which will lighten up nicely - even the car may change noticeably. This test is purely to give you a feel for what will happen if you spread the IR light; it's not intended as the permanent solution. Incidentally, with LED illuminators, I find it's often worth checking that all the diodes are functioning correctly, so I will generally point the camera 'off axis' towards the lamp, and you can then see if any of the diodes are dead. Oh and by the way, if you see a huge white cat running across the road ... it's probably a fox!

Ain't that the truth! I once spent two weeks solid terminating loose tube fibres - and that was when the epoxy had to cure for a minimum of 24 hours before you could polish it off. At the end of the job I realised there's a much easier way to do it .... sub contract!!

With conventional weatherproof housings, I usually use a squirt of acrylic sealant inside the cable glands before they're tightened up, and for compression seals, a thin application of silicon grease will generally stop anything from getting in. If you're doing maintenance, remember to wipe it off first otherwise it gets everywhere, and it's a b****r to wash out

Light transmission through optics .... and network bandwidth restrictions ... all in one thread

Hi sjones9, Did you volunteer for this assignment, or was it a short straw job? I'm guessing there are two distinct issues here, namely the selection of appropriate technology, and perhaps more importantly, a proper interpretation of the sites operational requirements. If you have some technical knowledge, then you're bound to get loads of useful advice on this forum, which will hopefully point you in the right direction. Personally I would advise a strong degree of caution, simply because on the little information you have provided so far, if you throw a system togethor which appears to do exactly what the M.D. wants, if at some later stage it all goes horribly wrong, who due you think will be expected to 'carry the can'? Provided you can adequately cover your posterior, I'm sure you can expect to receive plenty of advice. If not, you should seriously consider employing the services of an independent expert, then at least it will be his backside that gets a kicking, if your security is compromised. Incidentally, from the information you've provided so far, it would be very difficult, if not impossible, to give you any absolute answers; there are just too many as yet unspoken factors involved. (I hope this doesn't sound too negative - I just don't want you to think that it's as straightforward as putting a camera on your front door)

Hey Basil, Looks like somebodys parked their red car on your driveway I noticed you've ordered up a relatively narrow beam IR illuminator, and given that you appear to have a fairly wide ish lens on the camera, you may have problems lighting as much as you want. Maybe if you give it a go then post back with your results; if you need to fiddle with the lighting, we may be able to come up with some suggestions. Interesting to see how the focus drops off towards the edge of the picture. If the camera manufacturer had fitted a good quality lens, you'd probably have seen quite an improvement overall, but then of course, the price would probably have shot up

Any 'hot' filament bulb will emit copious amounts of Infra red (for example, tungsten halogen bulbs). Cooler sources such as fluorescent tubes, low / high pressure sodium, metal halide are all virtually useless for IR work. The short answer is if you lit an area to around 25 lux using filament bulbs, or as an alternative low energy fluorescent tubes, the filament illumination will always provide the brighter image for a Black and White camera, simply because the bulb is emitting plenty of non visible Infra Red, which the camera can pick up. In practice, it is generally the quantity of light, and not simply the frequency of light, which will dictate whether the image looks dark or not. If you lit a room with reflected blue light, or covert IR light to the same level of illumination, the pictures produced by a suitable Black and White camera would be equivalent, although the 'grey' levels would appear different depending on the frequency reflectence of individual objects. So as an example red curtains may look almost black under blue lighting, and almost white under IR lighting.

The only slight problem with using a 'focus meter' is that whenever you need to set a lens focus to an abstract point (to make best use of the available depth of field), the unit will be fooled by the largest 'sharp' object, and not necessarily the point you actually want. Sometimes too much technology can end up doing your head in!

The mobile (cellphone) service providers paid the UK government an absolute fortune for licences to operate 3G, and then realised they didn't have a "killer application" to quickly recoup the money I had a chat with one service provider recently and quite frankly, when it comes to the potential for 3G / Security monitoring, they simply haven't got a clue. Their idea for promoting the service is to stream soccer matches to a phone, with an image so small, you can just about see the players, much less the ball As it stands, I've been told that existing UK data transfer rates on 3G are currently 256k, with 512k due on stream sometime in the summer (given for what passes as a British summer, that could be anywhere between April .... and 2007). The technology is there, but service coverage is still likely to be a problem for some.

Hi Kaysadeya, The AC connector looks like a fairly standard 5 pin DIN (originally a german connector, now pan european). How many do you want The silver plug is I think an EIAJ standard japanese connector ( think it used to be called an 'hirose' or something similar) which is not easy to get hold of; have you tried the spares department for Pentax lenses (Cosmicar lenses are Pentax!). The black plug again looks like a standard 4 pin DIN, and the large multipole, is a fairly common industrial connector, often used in MIL spec applications. I guess the mini 8 pin connector is just the latest cheapo japanese offering, again, Pentax spares may be able to supply.

Ain't that the truth guys Just to clarify a couple of points though. The NTSC colour system (525 lines), PAL & SECAM (625 lines), refers to the number of horizontal lines stacked one above the other, that make up the picture. The horizontal resolution (H.R.) of a camera refers to (if you like) the number of points that can be resolved along a line ( a bit simplistic but I'm sure you get the drift). With this in mind, the higher the horizontal resolution of the camera imager and its associated circuitry, the sharper the image will appear (if correctly set up, focussed, exposed etc. etc.). Whilst CCTV cameras generally limit at or around 600 lines H.R., broadcast cameras actually go way beyond this, so although they still use the 525 or 625 line scanning systems, the horizontal resolution may be 700+ lines. An example high end industrial / broadcast camera is on the following link:- http://www.ikegami.com/br/products/sdtv/sdtv_camera_frame3.html Now what could we do with a 750 line resolution colour camera?

Forgive me for being picky, but the 'NTSC' bit refers to the colour system, and doesn't relate to the specific resolution of a camera. So you can have 330 line, 460 line, 520 line (or greater) 'NTSC' cameras; likewise the pixel count for the imager is quite obviously not going to be affected by the maximum aperture of a lens. A 412k imager will still be a 412k imager whether you use an f0.95 or f1.4 lens. If a manufacturer (or expert) states that the f0.95 lens has 2.17x more light gathering ability than an f1.4, far be it from me to argue. That said, coming back to DVR Expert's original point, whilst the larger aperture will theoretically offer this huge jump in light gathering ability, if the lens elements, coatings and design are total c**p, most of that apparent advantage will count for little when looked at in relation to light transmission through the lens. It's also worth remembering that at larger apertures, overall optical performance is somewhat reduced, and the 'depth of field' will be minimal. As regards the percentage of target required to occupy the picture for effective identification, this problem is generally nothing to do with simple engineering principles, but in most cases, the camera / lens combination are either incorrect, located in the wrong place, or set up in a less than ideal way; and that is down to lack of knowledge or experience on the part of the installer.

So that's where I've been going wrong all these years, I didn't have the book I'm a bit confused McJannet, what has lens light transmittance got to do with the PAL / NTSC signal system, and indeed what relevance does 'T' have to "PAL / NTSC resolution"? I don't think that lens transmittance should be any more a worry on your new Nikon D70, than it was on my Nikon F2S when I bought it in 1977. Happy snapping!

Manual Iris lens .... o.k. Electronic Iris (EI) or Automatic Electronic Shutter (AES) switched on in the camera???? Herminshs, what type of camera is it? do you have a link or pictures?.

I don't know the camera, but it sounds like the Electronic Iris function is switched off (assuming it has one )

DVR, I've got a funny feeling this could end up as one of those circular arguments where we end up disappearing up our own ..... Lens manufacturers have historically always quoted maximum apertures (f1.x), but in general terms, it's almost unheard of for them to release detailed engineering information relating to light transmission through their optics (I know I have seen 'T' figures quoted recently, but I just can't remember where I've seen them). In a funny way, this is probably no bad thing, considering that many have problems with even basic optical principles, and if yet more information was made available, we'd probably all end up as unbearable lens snobs. The biggest problem with CCTV equipment in general, is we can get so hung up on what's written on the spec. sheet, it's easy to assume that some thing is going to be good (because it says so on paper), without at least taking the trouble to test whether the claims are true. Quite frankly, it doesn't much matter to me whether a lens is f1.2, f1.4, f1.6 or f1.8 unless it is either required to work at maximum aperture in very low light conditions, or a camera is being deliberately used with a high shutter speed to freeze motion, in which case the lens iris may need to operate at its optically inferior maximum setting, just to get a picture. Ideally, any lens will produce its optimum optical quality at or around it's mid aperture setting (normally around f 5.6 ish), so if there is enough light for a lens to operate at that aperture, in theory, it should be pretty much the same result, whether you are using an f1.4 or f1.8 maximum aperture lens. There is no substitute for personal experience, so if you get the chance to test comparable lenses on identical cameras, you can quickly see whether a particular optic is worth the extra bucks or not. If I'm given the choice (and the budget), I will always go for a larger format lens first knowing full well that the optical quality will immediately appear much better (e.g.on a 1/3" CCD camera, using an 8.5mm f1.5 'C' 2/3" format, rather than an 8mm f1.2 'CS' 1/3"). If your guys are able to get hold of 'useful' transmission data for any of the major lens manufacturers products, that could be interesting to say the least.

kaysadeya, The suggestion for building a 'hardwired' controller, was to try and keep the cost down, not necessarily offer the most "sophisticated" solution. If you want to use the DVR on 422 you will need a suitable protocol convertor, and I personally wouldn't even begin to contemplate building that, if it's possible to pick up an off the shelf adaptor at reasonable cost. I can't suggest any sources off the top of my head, but if I come across anything I think might be suitable, I'll post back.

Judge for yourself http://www.bbc.co.uk/apprentice/ Incidentally, I just remembered that the name Amstrad was from Alan M. Sugar Trading. Might be useful for any fellow Brits if it comes up in a pub quiz.

Herminshs, The programm CCTV wants to record is called "The Apprentice". A gentleman by the name of Alan Sugar (Sir Alan actually), is currently participating in a reality TV show where each week he fires a would be apprentice that doesn't quite make the grade. The show started off with (I think) 6 guys and 6 gals, and at the end of the run, the one who is left standing will get a job working for Sir Alan. He originally made his fortune in the early '80's by launching a computer company called Amstrad Electronics (at that time, he was to computers in the UK, what Apple was in the States). As a 'no nonsense' businessman, his current fortune is estimated at something in excess of US$ 1.25bn. I guess some jokes just kind of lose it in translation ... And yes, as far as I am aware, Packard Bell are alive and kicking this side of the pond, unlike Tivo, which I have yet to encounter other than by reputation.

So rory, it looks like we're all aiming to move to Manchester then

CCTVINSTALLER, ever thought of using an Amstrad Computer ? (Brit joke guys!)

yep! ish. The f stop is directly related to focal length and diameter of maximum aperture, which is usually dependent on the maximum diameter of the front optic. If I remember correctly, the old 'T' system specifically relates to transmission of light, which can be affected by loads of factors such as glass density / quality, multicoating, number of elements (individual lenses), element profiles etc. f stops are a nice convenient way of describing a relatively simple mathmatical principle, but in practice they don't tell the whole story. That said, the theory is that f 5.6 on an 8mm lens should be equivalent to f 5.6 on a 25mm lens, but past experience suggests to me that this need not necessarily be the case. Make things simple I say, life's far too short

I don't know if this will help at all, but I'm sure I've seen a 10 channel video + audio sequential switcher a couple of years ago, which I think was made by GBC (US company). There are certainly audio mux units available, but to be honest, I've never had need for them, and never bothered to keep any info on them.

kaysadeya, I'm suddenly thinking sledge hammers and nuts. If you just want to control zoom and focus, would you consider making up your own direct drive box? One switch for (each) lens selection, two switches for zoom and focus, a bit of multicore to each lens, and a plug in regulated power supply unit. If you don't mind messing about with a soldering iron, you could make a controller in a couple of hours. You wouldn't really consider relay drives unless the cable runs were excessive. Just a thought.

Not regulated this side of the pond rory, but take your point. Incidentally, apologies guys for my earlier posting about a restricted access forum; sometimes my slightly ironic Brit sense of humour gets the better of me