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Thread: how ??????

  1. #1

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    David Owings

    how ??????

    Was setting up on oure street to practice bracketed photos. a car came by and hand held just tried to hold still and get the streak. Question to all you pros out there? why is the cars plate not blurred/streaked like the tail lights. Why can I see the trash can with the plate just hanging there. (hand held Cannon EOS T2i) single shot. If I could know what I did and do it with intention it could be a cool techhow ??????nique All I did to this pic was crop it a little

  2. #2
    dje's Avatar
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    Re: how ??????

    David my theory is this - from the EXIF information in your image, the flash fired. This is probably what illuminated the number plate momentarily. Also from the EXIF info, the shutter was open for 2 secs and you can see the trash can because it was captured after the car went past it but before the shutter had closed.

    I don't think you've discovered any new laws of physics

    Dave

  3. #3
    Momo's Avatar
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    Re: how ??????

    Now there's something you don't see every day. I agree with dje, as the flash fired freezing the license plate in time. The car is moving too fast and too dark to be noticed by a sensor whose sole purpose in life is to capture light.

  4. #4
    ktuli's Avatar
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    Re: how ??????

    I agree with both of the previous comments. Additionally, remember that license places are designed to be reflective, so it was much much more sensitive to the flash than anything else in the scene... which is why it stands out so much.

    - Bill

  5. #5

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    Re: how ??????

    Technical question: if the car was "passing by", why are the light streaks not crossing the entire image from the left to right border instead of starting were the licence plate is. It looks to me as if the car sat were the plate is and started moving from there???

  6. #6

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    Re: how ??????

    Quote Originally Posted by wlou View Post
    Technical question: if the car was "passing by", why are the light streaks not crossing the entire image from the left to right border instead of starting were the licence plate is. It looks to me as if the car sat were the plate is and started moving from there???
    Might this be something to do with the synchronisation of flash and shutter..?
    From my camera (D7000) manual:
    "REAR (rear-curtain sync): Flash fires just before shutter closes, creating a stream of light behind moving light sources... If... not... flash will fire as the shutter opens". It includes two pictures illustrating the effect, which is a bit like the numberplate, though with the whole car visible.

    So, shutter opens and flash fires as the car is at the point where the licence plate shows, shutter remains open until car reaches point where the light trails end...? Does that work..?
    Ian

  7. #7
    dje's Avatar
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    Re: how ??????

    Quote Originally Posted by ktuli View Post
    I agree with both of the previous comments. Additionally, remember that license places are designed to be reflective, so it was much much more sensitive to the flash than anything else in the scene... which is why it stands out so much.

    - Bill
    Yes Bill the reflective number plate is the only explanation I can see for the number plate only showing up. I am a little surpised there's not at least a faint outline of the car though - perhaps it was black ?

    Dave

  8. #8

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    Re: how ??????

    Thanks, Makes sense about the flash. LOL was not figuring I found something new just could not figure out how. The car was not at a stand still as one post sugested but was only moving about 15 mph

  9. #9

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    Re: how ??????

    The lights start where the car was when the shutter was triggered. The area behind the license plate is in the street light and was exposed while the car moved away. Like photographing a bird in flight. You still see what was behind it at the time.
    If the shooter had triggered earlier and waited longer you would see the tail light trace go all the way through the frame. Everything would also be brighter because the shutter would be open longer.

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