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Exposure capture range of a typical B&W analog camera module

Discussion in 'Hobby Electronics' started by [email protected], Oct 5, 2007.

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  1. Guest

    I recently purchased a Swann D-CAM which is just a cheap plastic case
    in the shape of a security camera with a relatively small CMOS sensor
    module sitting at the front. I put the module into a smaller case and
    installed it facing out of my front window.

    Next day it was obvious that the sunlight was a little too much for
    the sensor, it is clearly overexposing (although not horribly). I'm
    thinking of sacrificing some night-time sensitivity and SNR by either
    placing a filter over the lens, or perhaps some window tint on a small
    section of the window glass.

    The specs say the shutter range is between 1/60 and 1/15000. Is this
    typical for a CMOS module? Would a CCD module fare better in this
    regard?

    This is just an experiment at the moment, the D-CAM cost all of $29 as
    Tricky Dicky are clearing them out. In the long run it would probably
    be better to use something with an electro-mechanical iris and the
    ability for my computer to control exposure based on the portion of
    the frame it wants to expose for (ie, if it's sunny then blow out the
    background, I want to see the person's face, not detail of my concrete
    driveway!)

    Any tips appreciated... my front door was forced by an unknown
    intruder while I was standing right behind it.
     
  2. Phil Allison

    Phil Allison Guest

    ** You need every bit of low light sensitivity you can get.

    ** It is quite unrealistic to expect to see identifiable faces on a cheap
    B&W video camera UNLESS that face just about fills the frame and is close
    to square on.

    What you are playing about with is total waste of time.

    ** That is terrifying.



    ........ Phil
     
  3. rowan194

    rowan194 Guest

    We have a front porch light that's on at night so low light
    sensitivity isn't as important. I will also be using a PCI capture
    card with frame averaging which will help reduce noise in static areas
    of the image.
    Actually it shows up reasonable quality faces, although the shades
    that you would expect are a little off - I'm assuming this is because
    the module is IR sensitive and it's picking up more than visible
    light.

    I was considering a module disguised as a peephole, but the potential
    to aim it at anything besides horizontal is probably nil, which means
    that it will catch the afternoon sun and could potentially damage it
    in the long run. Perhaps there's a module with an iris available which
    would work towards solving this issue - general auto-iris until it's
    triggered by movement within a specified area, then track and expose
    for that moving object.
    Yeah, it wasn't much fun. I also happened to be holding a camera in my
    hand but didn't manage to fire off a shot. I'm lucky he didn't take
    the camera, or become enraged that I had captured his face. A quick
    raise of the tyre iron over his shoulder, a couple of lunges at me,
    then he was off like a coward.

    Next time I'll be making plenty of noise to make it obvious the place
    is populated, rather than thinking "who is outside, I'm going to
    surprise them and take a photo......."
     
  4. Phil Allison

    Phil Allison Guest

    "rowan194"
    "Phil Allison"

    ** Fraid it still very much is.


    ** You just need to get that burglar to stand real still and smile at the
    camera.

    What's so hard about that ?


    ** You are not talking about the same issue I am.

    Cos you are too dumb to understand it.



    ** Anyone see a contradiction here??


    ** Sorry - who was the coward ?


    ** Do something useful - you pathetic wanker.

    Like secure you door properly and or add a steel security door.

    Have an outside alarm bell you can trigger with a button.

    Using a cheap BV&W video camera is useless, or even WORSE than useless.



    ....... Phil
     
  5. Sally

    Sally Guest

    What on earth is wrong with you? Are you completely incapable of having a
    normal conversation?
     
  6. Phil Allison

    Phil Allison Guest

    "Sally = the anonymous, libelling bitch from Newcastle "

    ** Nothing at all was wrong with my post until some totally * asinine bitch
    * SNIPPED it to pieces and entirely removed all meaning. Really pathetic
    to do that JUST so you can then post mindless abuse of the author.

    Only the very worst scum on usenet pull that stunt.


    ** Usenet is not some "chat room" for anonymous retards, like Sally -
    there are in fact no " conversations " here at all.

    Sally is too dumb to have anything to contribute

    - so **** OFF BITCH !!




    ........ Phil
     
  7. Terryc

    Terryc Guest

    Direct sunlight? If so, try moving it so that it isn't exposed, or
    install a shade over the spot where the direct sunlight comes from.
    You can only try this and see what happens.
     
  8. rowan194

    rowan194 Guest

    It's mainly reflected off the road and driveway surface - there's only
    a small amount of sky framed, and that's not the only portion of the
    screen that is blowing out. I only have a limited range of movement
    with positioning the camera because it's at the top of a window frame
    behind glass with decorative crosses, but it *is* located high and
    pointing down rather than the reverse.

    It would be handy if these things had some sort of rudimentary iris so
    you could adjust it to be sensitive to low light (fully open) or
    insensitive to bright light (nearly closed)... I guess replacing it
    with a pinhole module would have a similar effect to the the latter.
     
  9. rowan194

    rowan194 Guest

    Not sure why I'm bothering to reply to your trolling, but I'll mention
    that I'm also considering a prominent flashing LED just below the
    camera, so that once the PC detects someone has moved into the
    appropriate spot it activates. Person sees the "movement" in their
    peripheral vision, then turns to face the source. Snap
    Typical bully, all bark and no bite.

    Oh yeah, the intruder was also a bully.
     
  10. Phil Allison

    Phil Allison Guest

    "rowan194"
    "Phil Allison" <

    ** YOU are the one trolling for bullshit info.


    ** New silly facts - all dreamt up as he goes.



    ** Only total nut cases ( & guard dogs) deliberately confront intruders.

    You qualify in the former.



    ....... Phil
     
  11. Guest

    Explain it then fag boy , should I allert Roddles to your post ?
    I expect most of the group don't care what you post but some might
    and will be suitably amused at your sillyness
    about you certainly , take more meds fagboy and do try to make some
    rational with out being a putz
    you the last time someone called , perhaps when next you meet meet
    fagboy might open the security gate ?
    speaking of wanker have you felated anyone of late philthy ?
    wrong again philthy , it is not a solution but a learning process
     
  12. Guest

    I suggest you go have a bex and a lay down philthy , if not then
    expect another pounding on your security gate button... coward.
     
  13. Guest

    I've found a CCD module with a 1/50 to 1/100,000 shutter speed range.
    It's capturing a fully sunlit street at the moment and there is no
    large scale overexposure like with the CMOS module - the only obvious
    point is the sun on a white verandah post. The dynamic range seems to
    be greater also, the output is of lower and more even contrast rather
    than being harshly clipped at the dark and bright ends.

    Most importantly, you can clearly make out facial features in this
    brightly lit situation.
     
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