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phred

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Posts posted by phred

  2. Posted

    personally, if i was going to try plywood i'd install it on the inside of the sheetmetal so it wouldn't look so nasty..... but, i probably wouldn't use plywood myself.. i'd use 2 lengths of unistrut horizontally on the inside between the building's framing and thru-bolt the camera mount thru the sheetmetal instead.

     

     

    Good man ---- You're hired

     

    Attaching the camera housing in that way will ensure it becomes part of

    the same Faraday Cage so all voltages will rise and fall at the same time,

    just as the experts at www.lightning.org recommend.

     

     

     

    Also see this post by Rooney http://www.cctvforum.com/post-49997.html&highlight=#49997 who lives in an area where lightning is an issue.

     

     

    .

  3. Posted

    Excess light alone should not cause overheating by the mechanism you

    describe ie 'overvolting'

    CCDs have a very sharp cutoff in response beyond which additional light

    will not increase the output. The excess light will however cause additional

    heating as visible light is absorbed by many materials and becomes IR

    (quantum mechanics). It is actually pretty difficult to get rid of all IR

    without cooling the CCD.

     

     

    There are many different designs of CCD and some can tolerate more

    heat than others. Those with microlenses and filters made of plastics, for

    example, are more easily damaged by overexposure.

     

     

    The problem with using your video cameras is that they have not been

    designed for 24/7 use and the CCDs will not be designed with longterm

    overexposure in mind. I also suspect they may suffer from image burn as

    a result of viewing the same scene for long periods.

     

     

    (good questions btw )

  6. Posted

    Ok jisaacmagee, my misunderstanding.

     

    Lightning is not something I would bother about here either. Doing a

    proper protection job is quite involved and at the end of the day you can

    still end up with toast.

     

    My objection was to the pseudo science nonsense and false claims about

    lightning protection and 'building zap' by CSG – I think the guy has been

    reading too many Marvel comics.

    In an area where lightning strikes are a real threat his suggestion would

    actually make matters worse.

     

    Regards

  8. Posted

    If you have ever used a magnifying glass to focus the sun on a piece of

    paper you will understand the problem. The damage to the CCD is usually

    caused by excessive heat build up as the lens focuses the sun on the CCD.

    I have tested some CCDs to destruction in a lab setup, usually they just

    stop working but just a few have exploded

     

    You really should do all you can to avoid pointing your camera at the sun.

    Reflected sunlight and car headlights are less of a worry - they just tend to ruin the image.

     

     

    Smearing is... as Kensplace says..

     

     

    Google 'CCD smearing' you should find some examples.

  9. Posted

    New York State has some of the best line men and electrical workers in the world, the NYC standards and safety requirements for electrical work in heavy and highway are strictly enforced. The statement of "licenses handed out for a couple of cereal box tops" based on one persons representation of their electrical/energy knowledge or lack of does not speak for the trade. Have a good and safe day.

     

    Thank you for the reassurance - I know from past experience that what you say is true.

    I was however, referring to licenses for security installers.

     

    Perhaps a more likely explanation is that CSG is not who or what he claims to be.

  10. Posted · Edited by Guest

    If that housing is the same on the inside as mine, then the camera is mounted on a plastic plate that snaps into metal guide rails. As the cam is screwed into plastic on mine, it never actually touches the metal of the housing, so grounding is not a issue (apart from cable grounds).

     

    Looks like it is the same housing, but could be a different mount inside.

     

    Only a good earth bond will give you protection from lightning. Plastic

    insulators are useless at very high voltage – the only thing that comes

    close are those huge glazed ceramic isolators you see on overhead power

    cables or the Soapstone blocks used at the bottom of high power

    transmitter antenna - they still need special grounding in case of lightning

    strikes.

  11. Posted

    CCD technology has been pushed so far into low light territory for things like thermal imaging, I can't see CMOS catching up for several years, if at all. Cmos does have advantages in almost every other respect now - like 250 times the contrast ratio and twice the bit depth. What I would like to see is more cameras that have both types of imager cmos for day and CCD for night.

  12. Posted

    oh ya I left out one more part in the steps with nylon screws and nuts.

    be sure to get like three or four nylon washers for each screw and put them behind the mounting bracket in between the aluminum and the bracket.

    this will give it complete isolation from the building to the camera housing. (no ground)

     

     

    OK, you got me, that was a wind up just to get me on my soapbox

  14. Posted · Edited by Guest

    [is there a big risk of lightning damage to security cameras mounted less than 20' up on a 2-story building? What's building zap?

     

    well, sensitive electronics (camera) bolted to a metal housing bolted to a metal mount screwed to a metal building with metal framing into the ground.....

     

    summer thunderstorm comes by and strikes the building, or even nearby,, a tree, the ground, camera might get tickled by stray voltages, might blow the cam.

     

    a insulator (plywood) will make your mount more ridgid, and provide some protection at the same time.

     

     

     

    Two of the safest places to be in an electrical storm

    Inside a metal clad building or a motor vehicle.

     

    The metalwork acts as an efficient conductor allowing the energy to

    discharge to ground.

     

    Attempting to isolate a camera from a metal building is a waste of time.

    There is no insulator that will hold back 100,000,000 volts. Even if you

    could do it you would then create a situation where, if lightning struck the

    camera, the path of least resistance would now be the cable from the

    camera. Not a good idea to put 100,000,000 volts into a DVR.

     

    There is nothing you can do that will 100% protect sensitive outdoor

    equipment from the effects of lightning – the best you can do is provide

    an efficient earth conductor.

     

    Suggesting that a plywood sheet is protection from lightning is simply

    nonsense. By all means use it to stabilise the camera but please, drop the pseudo science crap.

     

    CSG calls himself a professional licensed installer, I can only assume that

    they hand licenses out in New York in exchange for a couple of cereal

    packet tops.

  15. Posted

    Apart from the fact they tried to sue the makers of java, and tried to sue sony, over CCD image sensors - if kodak had had their way, the cctv industry would have probably been in deep trouble...

     

    I was thinking more of the 'corporate culture'. HP used to be similar years

    ago while IBM were a bunch or arrogant *****

     

    For such a large company Kodak are pretty far down the lawsuit table

    compared with Microsoft and Intel. Surprising when they hold over 1000

    patents on camera technology alone. As for the Sony case they obviously

    agreed that Kodak had a valid point as they eventually paid up and signed

    a licensing agreement without going to court- same agreement was

    already in place with Sanyo and Olympus.

    Kodak also accepted some of Sony's technology as part payment.

     

    Courts also found in favor of Kodak in the Sun Java case.

    The same technology has been licensed to many, including Microsoft, for

    many years so why should Sun get it for free - Sun were effectively

    charging their own clients for technology belonging to Kodak.

     

    Many of Intel's lawsuits against Via failed despite their huge legal budget.

     

    Just thinking about it, I have lost count of the number of lawsuits Intel filed

    against Via and I don't remember too many succeeding.

  17. Posted

    Google 'Via chipset problem'

    I did, now YOU Goggle "Intel chipset problem" and give me a count on how many 'hits' you get.

     

    Most/many of the problems with the early Via chipset drivers were the 4in1 driver package from 5 or so years ago.

     

    Oh, as far as the "rocket science" part, I was using it in the extream.

    ----------------------------------------------------------------------------------

     

     

    I was not offering an opinion, just pointing you to possible explanations.

     

    There is no doubt that Intel wanted to maintain a monopoly on chipsets for the P4 and patented several technologies related to the PCI bus and the way data was handled. This meant that anyone attempting to make a chipset for the P4 had to pay license fees to Intel. Via considered this unfair and produced chipsets for the P4 without paying the license to Intel. Intel sued Via in several countries – Via counter-sued Intel.

     

    It is remarkable that Via managed to make a chipset at all for the P4 considering their acrimonious relationship with Intel.

     

    My opinion, for what it is worth - Intel may have a legal right to protect their patents but they have an unhealthy appetite for bullying their rivals.

  21. Posted

    ........

    All I need is a 12v camera that can look out of a car windshield, not be blinded by the sun, and see cars around me in their actual colors. Is that too much to ask?

     

    All you need is a camera with 1million:1 contrast ratio.

     

    A lens with 20 f stops.

     

    Effective resolution approx 600 megapixels with a 130 degree field of view.

     

     

    That should match the human eye but you still will not be able to look at the sun.

     

     

    sorry for being a smartass but hope you see the point.

  22. Posted

    No light = no image, unless you use a thermal imaging camera (you don't want one -trust me).

     

    You will need to provide some light but a low watt soft light from a small

    lamp is all you need. You can move it around for best results.

     

    Unfortunately the lux figures they give in camera specs are often exaggerated.

    Brand name cameras tend to be more honest so don't be confused by

    what looks like a lower spec for a higher price.

     

    There are some inexpensive b&w bullet cameras – ones without LEDs but

    with grossly exaggerated spec - they should give you a decent image. For

    better quality nothing will beat a proper box camera and lens.

     

     

    Just as a guide, bright moonlight is 0.1 Lux

     

     

    Btw my own kids would freak if they woke up in pitch darkness.

     

    good luck

  23. Posted

    You also need to look at what hardware they are actually using....

     

    Yep, There is no surer way.

     

    Just to add to those comments -

     

    One of the benefits of the H.264 cards is that they have to have good

    chips. There are few to chose from with enough power to encode H.264 in

    realtime. The TI DaVinci (DM64x) chips seem to be what most people have

    turned to and they offer very high performance (probably still the fastest DSPs on the planet).

     

    Mpeg4 cards are more of a problem as everyone and his wife got on the

    bandwagon, buying in cheap mpeg4 encoder chips. There are some good

    ones amongst a mountain of dross.

     

     

    Like the man says - you know for sure when you have full hardware

    compression running, I managed to run a 4 channel H.264 card, recording

    100frames/s 720X576 on a Semperon 1.8Ghz with very low %cpu.

     

    The one thing you have to be careful of is the H.264 codec used. The TI

    chip is not an H.264 ASIC. It is a complex 'system on a chip' that can run

    any codec you can write the code for.

     

     

    Writing code to run H.264 efficiently on the TI chip is a job for DSP

    engineers and is well beyond the reach of your average programmer.

     

     

    Those who buy in cards, write a GUI front end and use an off the shelf

    H.264 solution will offer poorer performance than those prepared to do

    the hard stuff.

  24. Posted

    Price difference can be more than 100%.

    Look at the price of intel Conroe CPUs – same core processor, some can run fast and some not so fast.

    There is a wide range of price/quality for CCDs

    Other factor in camera price is the performance of the processing chips inside the camera.

     

    If this was not the case then all cameras would be equal.

     

    Also survtech is right about Pixim, they are giving Sony a bit of a bashing at the high res. end of the market

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