Why do our cameras have shutters?

Discussion in 'Panasonic Cameras' started by DanGuy48, Aug 7, 2011.

  1. DanGuy48

    DanGuy48 Mu-43 Regular

    I mean mechanical shutters with moving parts. I sell a lot of different CCD and CMOS scientific cameras and they all control the speed of the exposure just by control of the chip electronics. Having a mechanical shutter, IMO, just makes the camera more complex, noisy, etc. What's the deal?
     
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  2. zpierce

    zpierce Super Moderator

    661
    Sep 26, 2010
    Minneapolis, MN
    Zach
    I'm sure someone will have a much better explanation than this but I thought it had something to do with the charge that builds up on the sensor as it's used during composition / preview. I believe this is the same or related to the flare you see on lights during long exposures. I believe the mechanical shutter allows for clearing that. I could be confusing this with other concepts so please call BS if I'm out in left field :)
     
  3. zpierce

    zpierce Super Moderator

    661
    Sep 26, 2010
    Minneapolis, MN
    Zach
    Ok, this got me curious to figure it out again and found a much more comprehensive answer than my ramblings:

    Most digital SLR cameras that use a mechanical shutter, however, use the mechanical shutter to control the amount of charge accumulated on the sensor as this simple mechanical device can be used to simplify the circuitry on the sensor itself thereby generally improving image quality and reducing noise.

    Why Digital Cameras Have Mechanical Shutters
     
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  4. nickthetasmaniac

    nickthetasmaniac Mu-43 All-Pro

    Jan 11, 2011
    There's been fairly solid rumours for a while now that the next-gen mirrorless bodies (perhaps GH3?) will have an electronic shutter...
     
  5. rpress

    rpress Mu-43 Regular

    76
    Jun 11, 2010
    Our cameras have an nMOS sensor. So far, only CCD sensors have interline transfer.

    So with an nMOS sensor without a shutter, the problem is twofold. First, there would be a rolling shutter; fast moving objects would be skewed when exposed, because the pixel wells would be integrating as the frame is read out. You see this when taking video. Second and most importantly, the fastest that a frame could be read out would be too slow; this would limit the fastest shutter speed to something like 1/60s.

    On a CMOS/nMOS sensor, the only true electronic shutter that I know of would be by using a full frame transfer sensor. This sensor would have twice the area of a normal sensor; I expect it would be costly.
     
  6. squeegee

    squeegee Mu-43 Veteran

    403
    Jan 26, 2010
    As far as i'm aware there's no real reason other than electronics isn't good enough yet. If you wanted to see what an electronic shutter can do, just look at a single video frame from your camera or take a still picture with a video camcorder. The shutter speed is slow and as mentioned theres read out skewage on moving objects. Right now, by having the physical shutter there it means the sensor sees black while the electronics read out so even though the read out takes time still the picture isn't affected by more light on the last lines/pixels. I personally can't wait for a good electronic shutter, quieter, less mechanics to break, smaller camera and more...
     
  7. ~tc~

    ~tc~ Mu-43 Hall of Famer

    Oct 22, 2010
    Houston, TX
    Many compacts use electronic or global shutters, and its a big reason they have such shutter lag.

    In a DSLR -type camera, that lag is completely unacceptable.

    That said, I'm not sure why the m43 shutter has to be so damn loud
     
  8. zpierce

    zpierce Super Moderator

    661
    Sep 26, 2010
    Minneapolis, MN
    Zach
    I'm as progressive a geek as there ever was but I'm not sure I'm ready for the shutter sound to go away :) I love that sound ever since I got my first non P&S camera, the g1.
     
  9. drizek

    drizek Mu-43 Veteran

    492
    Aug 5, 2011
    Big heavy shutter moving very quickly in small, cheap camera.
     
  10. Adubo

    Adubo SithLord

    Nov 4, 2010
    Globetrotter
    Andrew
    Im on the other side of the boat here. It'll be lovely if my PENs shoot like ninjas! No sound and very stealthy

    Sent from my iOS using Mu-43 App
     
  11. RT_Panther

    RT_Panther Mu-43 Legend

    May 4, 2011
    Texas
    NEX is louder than MFT...
     
  12. c5karl

    c5karl Mu-43 Regular

    144
    May 31, 2011
    Fairfax, Va., USA
    Don't forget that a shutter in a liveview camera is doing twice as much work as a shutter in an SLR. On an SLR, the shutter rests in the closed position, so it only needs to open and shut. On any liveview camera with a shutter, the shutter rests in the open position so that the sensor can be used for liveview mode. So snapping a picture requires the shutter to close, open, close, open.

    That may be an oversimplification. I know my old film SLRs actually re-cocked the shutter when the film was advanced. Not sure how this works on DSLR cameras. But it seems pretty clear that a non-liveview camera will require less work from the shutter than a liveview one.