Shutter speeds are something we take for granted, 5 seconds to 1/5000th of a second, we click and we get what we want. But it is useful to know a few of the geeky technicals so you don’t get caught out in certain situations. Take a look at this video, it’s a fantastic illustration of the inner workings for a camera.
You see the first shutter dropping down exposing the sensor followed by the second shutter sometime later. Because of the rate at which the shutters move, the shortest exposure with the entire sensor exposed at the same time is about 1/200s, after that the second shutter ‘chases’ the first, producing an image that is effectively rastered, on the sensor.
This has the biggest impact on your pictures when you introduce a speedlight as with very short exposure times part of the image will have been exposed and covered before the flash goes off giving you an image that is half bright and half dark, not good! That’s why your camera will have a max sync speed quoted to ensure you don’t run into this problem.
Less of a problem, but still interesting to note is that when you take pictures with high shutter speeds of fast moving objects you may notice a slight skew to the image since the bottom of the image will have been captured slightly sooner than the top! The wine cork in the video was a great example of of this!