X20 electronic shutter
In the specs it says the x20 has an electronic and mechanical shutter.
I had a good look at mine and it seems it uses the electronic for the opening shutter and the mechanical for the closing shutter. I don't see any mechanical movement at the beginning of an exposure (e.g. 4s) . After the exposure the camera seems to keep the shutter closed for a significant time (about same as exposure). I am wondering whether it does a dark frame subtraction to keep the noise down.