>>4093896Take two cameras in a room, you are going to use them both to film something on both for 1 second.
Method 1: turn lights of room off, start cameras recording (they are recording nothing since the light is off), turn the light on, wait a second, turn the light off.
Method 2: turn lights of room on, start recording on first camera, wait a second, stop recording, then do the same with 2nd camera.
In method 1, the exposure is controlled by the flicking of the lights on/off. Both cameras are essentially exposed at the same time.
In method 2, the exposure is controlled by the recording of the camera itself starting / stopping. There is some delay between as you from first camera to second camera.
It's all about how the sensor is getting the light. Either more all at once with mechanical, or little by little with electronic. Possibly consider film, where the film is always "ready" for exposure, and the mirror simply lifts up to allow that.
>>4093895see
>>4091755 or picrel
Still possible with mechanical shutters, they just tend to be so much faster it's not much of an issue. Some mirrorless also readout fast enough that it's not much of an issue. Electronic shutters also often have a slight decrease in dynamic range, and EFCS can alter how the bokeh looks, so you should ideally use mechanical when possible.
The mechanical shutter goes fast enough that the exposure is "all at once", where as with electronic it has to be exposed line-by-line, so by the time you get to the bottom / top, it's possible for there to be movement which will be captured.
