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Many point and shoot cameras have an electronic shutter. I only know of one good reason to have the electronic shutter: No flash synch speeds limitations; And that reason by itself i would think suffices to include it in any decent modern SLR.

  • Plus it is very fast and silent. – his Jan 6 '14 at 5:50
  • The larger the sensor, the bigger the disadvantage in terms of readout speed from the sensor and the more it negatively impacts image quality.. – Michael C Jan 6 '14 at 6:00
  • In other words, electronic shutters are inherently slow ? – angel rojas Jan 6 '14 at 6:06
  • No, large CMOS sensors output more data than small ones which takes longer to read out. The hardware needed on the sensor to allow each pixel to store the luminance value it just detected means more real estate on the chip for circuitry and less for the actual pixel well, thus decreasing image quality because of decreased sensitivity to light. – Michael C Jan 6 '14 at 6:26
  • This has all been thoroughly covered here before. See also photo.stackexchange.com/a/14320/15871 – Michael C Jan 6 '14 at 6:40
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First and foremost, without a mechanical shutter of some kind, there is no way to actually stop light from reaching the sensor after the exposure time has passed. With a purely electronic shutter, you continue to expose as you read out the image. Readout is fairly fast, but outside of specific cameras that use a high speed global shutter, often not fast enough to avoid exposure quirks and other artifacts.

With cameras that use a rolling electronic shutter, whenever there is motion that moves at a higher frequency than the shutter itself, you can get stuttering or jittery motion for the object(s) that are moving across the frame. The same wobbling that occurs with rolling shutters during video can result in torn or warped frames, especially if the photographer stops "holding still" while the exposure is still being read (and yes, this can still occur in the fraction of a second it takes to read out the whole sensor.)

The only way to GUARANTEE that your exposure time is 100% accurate, and avoid any unsightly artifacts caused by continued exposure during readout, is to use a mechanical shutter. Focal plane shutters are the most common, but leaf shutters in the lens would serve the same purpose with an electronic shutter. Anything that entirely blocks out light is necessary to ensure exposure functions properly. Modern global shutters with a very high speed readout are capable of replicating mechanical focal plane shutter behavior, however global shutters are not very common on still photography cameras yet. They are mostly used for video cameras, and the good video sensors with high speed global shutter tend to be very expensive.

There may come a time in the not too distant future where a good high speed global shutter that can read out the entire sensor in a small enough fraction of a second that they could effectively replace mechanical focal plane shutters. Until that time, mechanical shutters solve some critical problems, and are essential.

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    Only nitpicking because you used the words "guarantee" and "100% accurate" but a mechanical shutter causes exactly the same artifacts as a rolling electronic second curtain (e.g. when the camera moves as the shutter is closing) it's just it moves about 4x faster, meaning the artifacts are 4 times smaller. – Matt Grum Jan 6 '14 at 9:43

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