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CCTV Issues

Discussion in 'Multimedia, Projection, and Show Control' started by themuzicman, Dec 30, 2007.

  1. themuzicman

    themuzicman Well-Known Member

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    For the production I am in currently, I decided it would be neat to rig up a CCTV with night vision capabilities so that our stage manager could get a better view of the stage. I acquired two cameras, and am now in the process of trying to get them to work. I didn't go any research into the subject before hand, but upon getting them, I learned that they need both D.C. power and BNC connectors. I got the proper transformer to make them power up, but here is my problem: I do not have any video monitors. I got a BNC to Coax connector, but I cannot get it to transmit signal. I have two cameras, a massive outdoor one, and a smaller indoor camera with 50ft range. They both transmit static and fuzz, but in the smaller camera, I can see a blurry outline of my hand when I wave it through the field of vision.

    here is what it comes down to:
    Do I need to go out and buy an actual CCTV monitor, OR can I make it work with a regular TV and some hardware.

    Thanks for all help and happy holidays!
     
  2. mbenonis

    mbenonis Wireless Guy Administrator Premium Member

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    It's going to depend on what type of video the camera is putting out. I'm very much inclined to think it's a standard NTSC video signal, in which case all you need is a BNC to RCA adaptor to plug it into the AV input of your TV. Let us know if that works.
     
  3. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    For the infrared or night vision camera, it's a common practice to hang one or two 50° ERS on the balcony rail or as flat as possible frontal position, then gel them with primary red, blue, and green gels. Run the dimmer at full, and if visible light still comes out, add another layer of RGB or Neutral density.
     
  4. avkid

    avkid Not a New User Fight Leukemia

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  5. mbenonis

    mbenonis Wireless Guy Administrator Premium Member

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    We have two of these wonderful fixtures at our theatre. They get used once a year for the Lighting Technology class when we talk about types of instruments. THen they go back into their corner.
     
  6. kwotipka

    kwotipka Active Member

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    Why gel tungsten lights with Red Blue and Green? It seems that if you are going for the near IR portion of the spectrum then Double deep red is what you want. Adjust level for taste.

    Actually what you need are IR emitters. These are small banks of IR LEDs that kinda look like a color wash fixture.

    As far as your other problem, all you should need to do is run a coax cable from the camera to the video input (yellow jack on the back of a TV).

    Make sure that you are getting enough DC to the cameras when they are installed. One of the problems with going 12VDC vs a 24VAC system is that the DC falls off quickly over distance and as the load is increased.

    Another thing is to make sure that the lenses are in focus (if they can be removed). That would generate a blurry or fuzzy image and not snow. Snow sounds like you are trying to feed into the RF port (Cable TV) of a television. (RF != Composite).

    Lastly, you will want to focus under your IR source and not under normal lighting.

    kw
     
  7. derekleffew

    derekleffew Resident Curmudgeon Senior Team Premium Member

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    In the theatre during a complete blackout (and there really is no such thing, by the way), even a double layer of AP#8350 (R27, L106) will allow visible red light onto the stage, which may be objectionable. Hence R,G,B color filters. I agree, IR emitters are the best, and costliest, solution.
     
  8. kwotipka

    kwotipka Active Member

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    I am going to have to try this next time I am on set. I would love to see a spectrum plot and transmission % of what is coming out of the fixture after this mix.

    kw
     
  9. icewolf08

    icewolf08 CBMod CB Mods

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    Well, subtractive color mixing theory says that if you really did use the 3 primary colors to filter the light you will be left with no visible light. You don't actually need to use 3 gels, but 2 because in theory if you put one primary color in you have filtered out the other two, so you just need one other to filter out the first. If you put in a primary green you have filtered out the red and blue, so if you put in a primary blue with the green you have now filtered all the visible light.

    The other important thing to think about when doing this is that even with a fixture like a Selecon Pacific gels convert light into heat, and if you filter out all the visible light you are making a lot of heat so the burn out potential is very high. If you are setting up a light to be an IR illuminator that is going to be dedicated to that purpose you might want to invest in dichroic filters.

    Another thing to bear in mind is that there is usually more IR energy in the theatre than you realize. Runlights back stage, exit signs, tv monitors, etc. all bleed IR energy. We have never needed an illuminator even in complete blackouts. We use a simple IR capable security camera and there always seems to be enough IR energy to be able to see black drops moving in blackouts and all that. So test before you get into setting up an illuminator, because you may not need it and then you don't have to dedicate an instrument to that.
     
  10. silvrwolf

    silvrwolf Member

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    Make sure your camera is connected to a video input on your tv not the antenna jack. FYI a video connector will be a yellow colored female RCA jack. You will have to convert the other end of your coax cable to an RCA connector in order for your setup to work.
     

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